Comment by bux93
9 hours ago
Are you using the commercial version of Saxon? It's not expensive, and IMHO worth it for the features it supports (including the newer standards) and the performance. If I remember correctly (it was a long time ago) it does some clever optimizations.
We didn't use Saxon, I don't work there anymore. We also supported client-side (browser) XSLT processing, as well as server-side. It might have helped on the server side, maybe could even resolve some algorithmic complexities with some memoization (possibly trading off memory consumption).
But in the end the core problem is XSLT, the language. Despite being a complete programming language, your options are very limited for resolving performance issues when working within the language.
O(n^2) issues can typically be solved using keyed lookups, but I agree that the base processing speed is slow and the language really is too obscure to provide good DX.
I worked with a guy who knew all about complexity analysis, but was quick to assert that "n is always small". That didn't hold - but he'd left the team by the time this became apparent.
The final free version of Saxon is a lot faster than earlier ones too. My guess is that it compiles the XSLT in some way for the JVM to use.