The approach with using TSS_DEBUG or TSS_DEBUG_BRK should work with this code base too but maybe it's enough to just enable tsserver logging (initializationOptions.tsserver.logVerbosity) and inspect the log manually? It should allow you to see which requests are slow. But typically slowness is due to large number of files exposed to tsserver or very complex types. That would likely also show up as slow compilation using tsc on the command line.