Quick Take

Meta’s Muse Spark 1.1 (xhigh) and OpenAI’s GPT-5.5 (medium) represent two distinct approaches to frontier AI. Released on July 9, 2026, Muse Spark 1.1 is Meta’s first paid frontier model API, specifically engineered for agentic tasks. GPT-5.5, released earlier on April 23, 2026, maintains a slight edge in coding and complex benchmark performance but comes at a significant premium.

Benchmark Read

When comparing intelligence and coding capabilities, the two models are neck-and-neck. Muse Spark 1.1 holds an Intelligence index of 50.6 compared to GPT-5.5’s 50.4. In coding, GPT-5.5 leads slightly with 71.5 against Muse Spark’s 71.3.

Performance on specific benchmarks varies:

• GPQA: GPT-5.5 (0.926) outperforms Muse Spark (0.898).
• HLE: Muse Spark (0.451) leads GPT-5.5 (0.406).
• SciCode: Muse Spark (0.582) leads GPT-5.5 (0.535).
• LCR: GPT-5.5 (0.723) outperforms Muse Spark (0.633).

GPT-5.5 also demonstrates strong capabilities in specialized tasks, scoring 0.709 on IFBench, 0.575 on TerminalBench Hard, and 0.918 on TAU2. Math index data remains unknown for both models.

Cost and Speed

Muse Spark 1.1 is significantly more affordable, with a blended cost of $2.00/1M tokens, compared to GPT-5.5’s $11.25/1M.

In terms of speed, Muse Spark 1.1 is vastly more responsive. It delivers an output speed of 135.076 tok/s with a time-to-first-token of 0.824s. GPT-5.5 operates at 59.962 tok/s with a 3.231s time-to-first-token, making it less suitable for latency-sensitive applications.

Best Fit

Muse Spark 1.1 is the clear choice for developers building agentic systems where cost-per-token and low latency are critical. Its architecture is explicitly designed for these high-frequency interactions. GPT-5.5 is best suited for complex, non-latency-sensitive reasoning tasks where the specific benchmark strengths (like TAU2 or IFBench) are required for high-accuracy outputs.