Verdict
Built from the measurements below
- Accuracy is too close to call: Claude Haiku 5.5 scored 68.8% and GLM 5.3 Flash 67.5% on the same 80 questions, a gap within what chance alone could produce.
- GLM 5.3 Flash is 3.3× cheaper per question as billed ($0.00015 vs $0.00048), reasoning tokens included.
- Claude Haiku 5.5 generates text 2.3× faster: 192 tokens per second against 83.
- GLM 5.3 Flash starts answering sooner: 0.5 s to the first token, against 0.7 s for Claude Haiku 5.5.
Which should you choose?
Choose Claude Haiku 5.5 for faster streaming. Choose GLM 5.3 Flash for the lower cost per correct answer ($0.00022 against $0.0007), a quicker first token, shorter outputs (about 560 tokens per question against 873), open weights you can run yourself and more hosts to choose from on OpenRouter (34 against 5). The widest subject gap is in law: GLM 5.3 Flash answered 4 of 6 correctly, Claude Haiku 5.5 2 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap +1.2 points (z = 0.17). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.