we are experiencing some performance differences between different
versions of IMP.
IMP is a very large and complex piece of software... so you'll have to
be more specific - *what* is slower? Benchmarking, as Riccardo suggests,
is one option - another would be to profile your code.
IMP 2.0.1 seems to be much faster (up to 6 times faster) as compared to
versions 2.1, 2.2 and 2.3.1 (compiled with the "Release" flag).
What do you mean by "Release" flag? If you mean the cmake build type
("-DCMAKE_BUILD_TYPE=Release") then that doesn't do a whole lot (IIRC,
maybe some slightly different compile options on Linux; on Windows it'll
change which C runtime you link against). What will make the most
difference is what IMP check level you build with; if you use
-DIMP_MAX_CHECKS=INTERNAL then the internal checks will definitely slow
things down.