I can’t reproduce this, I’ve created a new ServiceStack v4.0.54 Self Host Empty project, modified MyServices with your implementation, refreshed about 50 times but haven’t seen any slow requests over 20ms, Web Inspector is reporting each request between 4-12ms:
Yes, I have tried on another pc and it’s working fine, but when I turn on Request logger with Response logging it returns error when using ToOptimizedResult.
The serialization error was due to the Request Logger trying to serialize the non-serializable CompressedResult wrapper Response when EnableResponseTracking=true.
I’ve changed it to only serialize the inner response (i.e. instead of the IHttpResult wrapper) in this commit.