Bug: Claude Code Unusable With Large Context

Introduction

In this article, we will address a critical bug report concerning the usability of Claude Code, an application developed by Anthropic, when dealing with growing context sizes. Many users have reported a significant degradation in performance, rendering the application almost unusable as the context reaches a certain threshold. This issue severely impacts workflow and productivity, necessitating frequent restarts of Claude Code. We will delve into the specifics of the problem, explore the reported symptoms, and discuss potential causes and solutions. Understanding and resolving this bug is crucial for maintaining the efficiency and reliability of Claude Code in practical applications. This article aims to provide a comprehensive overview of the issue and its implications.

Preflight Checklist

Before diving into the details of the bug, it’s important to note that several preliminary checks have been conducted to ensure the issue is a genuine bug and not a result of other factors. The user who reported the bug has confirmed the following:

• A thorough search of existing issues on the Claude Code GitHub repository has been performed to ensure the bug hasn't been reported previously.
• The bug report focuses on a single, specific issue to avoid confusion and ensure clarity.
• The user is currently running the latest version of Claude Code to rule out any issues that may have been resolved in recent updates.

These steps are crucial in the initial triage of any bug report, ensuring that the issue is unique, well-defined, and reproducible on the latest software version. By confirming these preflight checks, we can proceed with a higher degree of confidence that the reported issue warrants further investigation.

What's Wrong?

The core issue reported is a significant performance degradation in Claude Code as the context size grows. Initially, Claude Code functions as expected, but as the user interacts with the application and the context accumulates, several critical problems begin to surface. The primary symptom is the terminal becoming unresponsive, with input lag increasing dramatically as the context size increases. This makes it difficult, and eventually impossible, to type commands or interact with the application effectively. Specifically, the user reported that at around 1,000 context units, typing commands into the terminal becomes noticeably delayed. As the context grows to approximately 15,000 units, the application becomes almost entirely unresponsive, with Claude Code updating its responses only every 10 minutes or so. This level of unresponsiveness effectively renders the application unusable for practical work. The need to restart Claude Code frequently to maintain usability disrupts the workflow and diminishes productivity.

This issue represents a critical impediment to the practical application of Claude Code in scenarios involving substantial context. The observed behavior suggests a potential bottleneck in how Claude Code manages or processes large contexts, possibly related to memory usage, computational complexity, or other resource limitations. Understanding the root cause of this performance degradation is essential to developing an effective solution and restoring the application's usability under realistic conditions.

What Should Happen?

The expected behavior of Claude Code is that it should remain usable and responsive regardless of the context size. A core requirement for any interactive coding environment is the ability to handle increasing complexity and context without significant performance degradation. Users should be able to interact with the terminal, execute commands, and receive responses from Claude Code in a timely manner, even as the context grows due to ongoing tasks and interactions. The current unresponsiveness issue, which necessitates frequent restarts, severely undermines this expectation and impedes the user's ability to work efficiently.

Ideally, Claude Code should be engineered to handle large contexts gracefully, employing optimization techniques to manage memory usage, computational load, and response times. This might involve strategies such as context summarization, efficient data structures, or parallel processing. The goal is to provide a seamless user experience, where the application remains responsive and usable, irrespective of the size or complexity of the task at hand. Addressing this performance bottleneck is essential to realizing the full potential of Claude Code as a reliable and productive coding tool. Without this improvement, the application's practical applicability will remain limited, particularly in scenarios involving complex projects and extensive interaction histories.

Steps to Reproduce

The process to reproduce the bug is relatively straightforward, which aids in the investigation and resolution of the issue. The primary step is to engage in typical tasks within Claude Code that gradually increase the context size. This involves interacting with the application over time, performing coding tasks, executing commands, and allowing the application to accumulate context from these interactions. The key observation is that as the context grows, the performance degradation becomes increasingly pronounced. Specifically, the user reported that the issue becomes noticeable around 1,000 context units and severe around 15,000 context units.

To reproduce the bug effectively, one can perform activities such as writing and executing code, debugging, exploring different functionalities of Claude Code, and engaging in extended sessions where the application retains a significant history of interactions. By replicating these scenarios, developers and testers can observe the performance degradation firsthand and gather more detailed data on the behavior of the application under increasing context loads. This will facilitate the identification of the underlying causes and the development of targeted solutions. The simplicity of the reproduction process is a positive aspect, as it allows for easy validation of any proposed fixes or optimizations.

Claude Model

The user has specified that the Claude model in use is Sonnet, which is the default model for Claude Code. This information is crucial for the development team as it helps narrow down potential issues that might be specific to certain models or configurations. Different models may have varying performance characteristics, and knowing which model is exhibiting the problem is essential for targeted debugging and optimization. The fact that the issue is occurring with the default Sonnet model suggests that the problem is not isolated to a less commonly used configuration, but rather affects a wide range of users who rely on the standard settings of Claude Code.

This context is valuable in prioritizing the bug fix, as a problem with the default model is likely to have a broader impact than an issue specific to a niche configuration. The development team can now focus their efforts on investigating the interaction between Claude Code and the Sonnet model, looking for potential bottlenecks or inefficiencies that may be contributing to the performance degradation. Understanding the model in use is a key piece of the puzzle in resolving this bug and ensuring the overall reliability of Claude Code.

Is this a Regression?

The user has clearly indicated that this issue is a regression, meaning that the functionality was working correctly in a previous version of Claude Code. This is a critical piece of information as it narrows down the scope of the investigation considerably. Regression bugs often point to changes in the codebase that have inadvertently introduced new issues or exacerbated existing ones. By identifying the specific changes that occurred between the last working version and the current version, developers can focus their attention on those areas, significantly reducing the time and effort required for debugging.

The fact that the application was performing well just a few days prior to the bug report suggests that a recent update or modification is the likely culprit. The development team can examine the version control history, compare the codebases, and analyze the changes made during that period. This targeted approach is much more efficient than a general investigation of the entire application. Regression bugs are often high-priority issues, as they represent a degradation in the user experience and can disrupt established workflows. Resolving this regression quickly is crucial to restoring the application's previous level of performance and maintaining user satisfaction.

Last Working Version

While the user isn't certain about the exact version in which Claude Code was last functioning correctly, they mentioned that the issue wasn't present just a few days ago. This temporal context is valuable even without a specific version number. It provides a timeframe within which the problematic changes are likely to have occurred. The development team can use this information to correlate the reported issue with recent updates or modifications to the codebase.

By examining the history of commits, releases, and deployments within the past few days, developers can identify potential candidates for the change that introduced the bug. This might involve looking at specific features that were added, performance optimizations that were implemented, or any other modifications that could have had unintended side effects. Even without a precise version number, this narrowed timeframe significantly reduces the search space and helps focus the investigation on the most likely areas of concern. The ability to pinpoint the timeframe in which the regression occurred is a crucial step in efficiently resolving the issue and restoring the application's previous stability.

Claude Code Version

The user has provided the current version of Claude Code as 2.0.50. This information is essential for the development team as it helps to precisely identify the software environment in which the bug is occurring. Knowing the exact version number allows developers to replicate the issue in a controlled setting and ensures that any fixes or optimizations are targeted to the correct codebase.

The version number also provides context for the regression analysis. By comparing version 2.0.50 with previous versions, developers can identify the changes that have been introduced and potentially pinpoint the source of the bug. This information is also valuable for users who may be experiencing the same issue, as they can verify that they are running the affected version. Providing the Claude Code version is a standard practice in bug reporting as it is a fundamental piece of information for effective troubleshooting and resolution.

Platform

The user has specified that they are using the Anthropic API as the platform for Claude Code. This is important information because it clarifies the environment in which the bug is occurring. Different platforms may have varying performance characteristics, and issues that arise on one platform may not necessarily manifest on others. Knowing that the bug is occurring within the Anthropic API helps the development team focus their investigation on the specific interactions between Claude Code and the API.

This information can also guide the testing process. Developers can prioritize testing on the Anthropic API to ensure that the bug is properly addressed and that any fixes do not introduce new issues in this environment. Understanding the platform context is crucial for effective bug resolution, as it helps to narrow down potential causes and tailor the solution to the specific environment in which the problem is occurring.

Operating System

The user has reported that they are using Windows as their operating system. This is another critical piece of information for the development team as operating system-specific issues are common in software development. Different operating systems have different architectures, libraries, and system-level behaviors, which can impact the performance and stability of applications.

Knowing that the bug is occurring on Windows allows developers to focus their testing and debugging efforts on this specific environment. They can examine Windows-specific factors, such as memory management, process handling, and compatibility issues, to identify potential causes of the bug. This information also helps in prioritizing the fix, as the severity and impact of the bug may vary depending on the operating system. Addressing Windows-specific issues is often a priority, as Windows is a widely used operating system, and bugs on this platform can affect a large number of users. The operating system context is an essential element in understanding and resolving software bugs effectively.

Terminal/Shell

The user has specified that they are using the VS Code integrated terminal. This information is valuable because the terminal environment can sometimes influence the behavior of applications. Integrated terminals, like the one in VS Code, have their own characteristics and interactions with the underlying operating system, which can affect performance and stability. Knowing that the issue is occurring in the VS Code integrated terminal helps the development team consider potential interactions or conflicts between Claude Code and this specific terminal environment.

This information also guides the testing process. Developers can prioritize testing Claude Code within the VS Code integrated terminal to ensure that the bug is properly addressed and that the fix does not introduce new issues in this environment. Additionally, understanding the terminal context can help identify potential workarounds or temporary solutions that users can implement while the bug is being resolved. For example, using a different terminal emulator might alleviate the issue in some cases. The terminal context is an important factor in the overall bug investigation and resolution process.

Additional Information

In the additional information section, the user stated “No response”. This indicates that there are no further details or context provided beyond the information already included in the bug report. While additional information can sometimes be helpful, the bug report is already quite comprehensive and provides a solid foundation for the development team to begin their investigation. The lack of additional information does not detract from the value of the report, as the user has already supplied sufficient details to understand the issue and its context.

The development team can now proceed with analyzing the reported symptoms, the steps to reproduce the bug, and the various contextual factors (Claude model, version, platform, operating system, terminal) to identify the root cause of the performance degradation. The absence of additional information simply means that the team will need to rely on the existing details and their own expertise to diagnose and resolve the issue effectively.

Conclusion

In conclusion, the bug report highlights a critical issue with Claude Code: performance degradation leading to unresponsiveness as the context size grows. The detailed information provided by the user, including the steps to reproduce the bug, the specific version of Claude Code, and the operating environment, offers a solid foundation for the development team to investigate and resolve the problem. The fact that this is a regression bug, meaning the application was previously functioning correctly, narrows down the scope of the investigation and suggests that recent changes to the codebase are the likely cause.

Addressing this issue is crucial for maintaining the usability and reliability of Claude Code, particularly in scenarios involving complex projects and extensive interaction histories. The development team can leverage the information provided in this bug report to prioritize their efforts, identify the root cause of the performance degradation, and implement effective solutions. Resolving this bug will not only improve the user experience but also ensure that Claude Code can effectively handle large contexts, unlocking its full potential as a powerful coding tool.

For more information on bug reporting and software development best practices, you can visit Mozilla Bugzilla Guide].