JDK-8293019 reduced the number of JVMCI threads which are spawned compared to C2 threads (via -XX:JVMCINativeLibraryThreadFraction).

The default setting often results in a single JVMCI thread being spawned.
For Graal, this can lead to significant warmup issues in the presence of long running compilations.

It might be reasonable to have at least 2 JVMCI threads (if possible).