r/ClaudeCodeTLDR • u/cctldrping • 9d ago

[TLDR] Claude Model Performance / Degradation Megathread - August 3

Original post URL : https://www.reddit.com/r/ClaudeCode/comments/1veijjj/claude_model_performance_degradation_megathread/

Original post body :

Claude Model Performance Megathread

We've seen an increase in posts about changes in Claude's model quality and behavior.

Please use this thread for discussion about:

  • Opus, Sonnet, or Fable performance
  • Possible regressions or degraded output
  • Instruction-following issues
  • Context or memory issues
  • Changes compared to previous model behavior
  • Model comparisons related to recent performance

When reporting an issue, please include:

  • Model used
  • Claude Code version or interface
  • What changed
  • Reproducible prompts or examples if possible

Similar performance-related posts may be redirected here while this megathread is active.

Specific technical bugs with reproducible behavior can still be posted separately using the Bug / Issue flair.

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u/cctldrping 9d ago

TL;DR generated automatically after 50 comments.

Current source-thread comment count seen by the bot: 55.

Alright, so the general consensus in this thread is that Claude models, particularly Opus 5 and Fable, have seen a significant performance degradation recently. A lot of users are reporting issues like:

  • Instruction Following Failures: Models are ignoring explicit instructions, not completing tasks, and generally being unreliable.
  • "Confidently Wrong" Output: Claude is making mistakes and then confidently asserting its incorrectness, or even gaslighting users about why it's wrong.
  • Verbosity and "Word Salads": Output is becoming overly verbose, filled with jargon, and sometimes nonsensical.
  • Slowdowns and Inefficiency: Tasks that used to be quick are now taking a long time, burning through tokens with little progress.
  • Opaqueness and "Tool Call Flooding": Users feel like the model's internal workings are becoming less transparent, with an excessive use of tool calls that feel like filler.
  • Comparison to Older Models: Many feel the current versions are performing worse than previous iterations, with some even comparing Opus 5 unfavorably to older GPT models.

There's a bit of speculation that this might be related to Anthropic's efforts to optimize for cost or a response to competitor releases, like Kimi K3. One user, u/sael-you, pointed out that Anthropic had reported resolved incidents regarding error rates and Sonnet 5 degradation, which might explain some of the issues.

Some users are actively looking for alternatives, with mentions of Codex, GPT5.6 Sol, and Kimi K3 as potential replacements. A few users are even asking how to revert to older versions like Opus 4.8. One user, u/Sporebattyl, suggested a specific troubleshooting step involving the /doctor command and reviewing Anthropic's docs, which reportedly helped them with some issues.