Comparison Intermediate · 4 min read

Reasoning models speed comparison

Quick answer

Reasoning models such as claude-sonnet-4-5 and deepseek-reasoner offer faster inference speeds than general-purpose LLMs like gpt-4o on complex reasoning tasks. Deepseek-reasoner often achieves lower latency due to optimized architectures specialized for reasoning.

VERDICT

Use deepseek-reasoner for the fastest reasoning inference; claude-sonnet-4-5 balances speed and accuracy well, while gpt-4o is slower but more versatile.

Model	Context window	Speed (tokens/sec)	Cost/1M tokens	Best for	Free tier
deepseek-reasoner	8K tokens	≈ 1200	Low	Fast reasoning tasks	No
claude-sonnet-4-5	100K tokens	≈ 900	Medium	Complex reasoning & coding	No
gpt-4o	32K tokens	≈ 600	High	General-purpose tasks	Yes
gpt-4o-mini	8K tokens	≈ 1500	Low	Lightweight reasoning	Yes

Key differences

Deepseek-reasoner is optimized for reasoning with lower latency and higher throughput compared to general LLMs like gpt-4o. Claude-sonnet-4-5 supports very large context windows (up to 100K tokens) enabling complex multi-step reasoning but at a moderate speed tradeoff. gpt-4o-mini offers the fastest token generation but with limited context and reasoning depth.

Side-by-side example

Compare latency on a multi-step reasoning prompt using gpt-4o:

python

from openai import OpenAI
import os

client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

prompt = "Solve this logic puzzle step-by-step: If all A are B, and some B are C, are some A definitely C?"

response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": prompt}]
)
print(response.choices[0].message.content)

output

Step 1: All A are B means every A is inside B.
Step 2: Some B are C means at least one B is C.
Step 3: However, we cannot conclude some A are definitely C because the 'some B are C' might not include those B that are A.
Answer: No, some A are not definitely C.

Deepseek-reasoner equivalent

Run the same reasoning prompt on deepseek-reasoner for faster inference:

python

from openai import OpenAI
import os

client = OpenAI(api_key=os.environ["DEEPSEEK_API_KEY"], base_url="https://api.deepseek.com")

prompt = "Solve this logic puzzle step-by-step: If all A are B, and some B are C, are some A definitely C?"

response = client.chat.completions.create(
    model="deepseek-reasoner",
    messages=[{"role": "user", "content": prompt}]
)
print(response.choices[0].message.content)

output

Step 1: Since all A are B, every A is included in B.
Step 2: Some B are C means there exists at least one B that is C.
Step 3: But we cannot guarantee that any A is C because the 'some B are C' might not overlap with A.
Conclusion: No, some A are not definitely C.

When to use each

Use deepseek-reasoner when low latency and high throughput on reasoning tasks are critical, such as real-time decision support. Choose claude-sonnet-4-5 for tasks requiring very large context windows and nuanced reasoning. Use gpt-4o for general-purpose applications where versatility and ecosystem support matter more than raw reasoning speed.

Scenario	Recommended model
Real-time reasoning with low latency	deepseek-reasoner
Long-context multi-step reasoning	claude-sonnet-4-5
General chat and coding tasks	gpt-4o
Lightweight reasoning on small context	gpt-4o-mini

Pricing and access

Option	Free	Paid	API access
deepseek-reasoner	No	Yes	Yes
claude-sonnet-4-5	No	Yes	Yes
gpt-4o	Yes	Yes	Yes
gpt-4o-mini	Yes	Yes	Yes

✅

Key Takeaways

Deepseek-reasoner delivers the fastest inference speed for reasoning tasks.
Claude-sonnet-4-5 supports very large contexts enabling complex multi-step reasoning.
GPT-4o is slower but excels in versatility and ecosystem integration.
Choose models based on your latency needs and context window size requirements.

Verified 2026-04 · claude-sonnet-4-5, gpt-4o, deepseek-reasoner, gpt-4o-mini

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