If you’re using the latest version of .NET Reflector, 7.1, then you are probably experiencing much slower startup times compared to 6.x and earlier. On my system, it takes about 15 seconds for it to start! RedGate is aware of the problem and are burning the midnight oil in order to fix it.
I did some quick profiling using xperf, aka Windows Performance Analyzer, and found an issue that accounted for 7 seconds of CPU usage on a Xeon W3520 (basically a Core i7-920 2.66GHz). Thankfully, no update is needed to work around the issue while RedGate comes up with an official solution. I’ve posted my findings and the quick fix to the RedGate forum. Try it out, and let the RedGate guys know if it helps! There is still much work to be done here, but the quick fix I’ve posted will hopefully provide relief in the meantime.
tl;dr … If you install the Reflector assemblies to the GAC using gacutil.exe, and run NGEN on them, then the startup time is significantly improved.