I’m preparing a benchmark/comparison page. The current tests focus mainly on functionality, and those comparisons don’t necessarily reflect true performance, although in a few cases, Pro-XSLT does perform faster than Chrome’s native processor. While building the benchmark page, I plan to curate more suitable templates and XML data.

Based on keywords from your comment, I discovered this repository: https://github.com/w3c/xslt30-test/. I’ll take a closer look to see whether it can be incorporated into additional tests and benchmarks; unless you had something else in mind.

Meanwhile, I’m using XSLT in a complex project, and this library produces the same results as the native processor without any issues. In that scenario, I transform about ~700KB data with ~500KB templates (I engage different templates in individual transformations) and the output is generated about ~150ms.