"perf" would be very helpful to help determine bottlenecks and performance issues.
https://slackbuilds.org/repository/14.2/development/perf/
perf is a userspace interface to the kernel's perf events. Performance counters are CPU hardware registers that count hardware events such as instructions executed, cache-misses suffered, or branches mispredicted. They form a basis for profiling applications to trace dynamic control flow and identify hotspots.