title: callgrind slow with instrumentation turned off
body: <p>I am using callgrind to profile a linux multi-threaded app and mostly it's working great. I start it with instrumentation off (<strong>--instr-atstart=no</strong>) and then once setup is done i turn it on with <strong>callgrind_control -i on</strong>. However, when I change certain configurations to try to profile a different part of the app it starts running extremely slow even before I turn instrumentation on. Basically part of the code that would take a few seconds with normal operation takes over an hour with callgrind (instrumentation turned off). Any ideas as to why that might be and how to go about debugging/resolving the slowness?</p>