Good for you. That does not mean that all workloads will have a max latency of 0.33ms.
By the way, I thought the kernel timer could be set to 1000Hz at most, so I don't understand sub 1ms latencies.
Most workloads will.
Btw, some OS`s boost threads. Threads that can occupy some time, but seconds sounds quite odd though.
Check if there are any threads set to realtime etc.