KLHPerformanceMonitor tracks the memory creation and CPU usage of all the mods running. You can print out a list of the top 10 mods, for memory usage or CPU time, in total or in the last 30.

The mod is inactive by default. To start it recording, run the command
/kpm load
. It will take a couple of seconds then print out some statistics. The data is collected in 5 second blocks, so wait a bit before printout out the results.

To print out the data, type
/kpm time total
/kpm time recent
/kpm memory total
/kpm memory recent

The mod works by hooking the OnUpdate and OnEvent handlers of all frames. There are lots of these (about 3000 with my addons), so there might be a slowdown to your system with this mod running. This is why it is not enabled by default.

There are thousands of frames, but you want to group them up by mod. KPM does this by looking at the first few letters of each frame, and grouping them together if they are the same. So all the frames starting with "CT_RA" or "DUF_" or "KLHTM" will be put in the same category.

Each print command will display out a list of 10 entries. Each entry has 4 values: the order in the list, from 1 to 10; the mod category, e.g. "CT_RA" or "Chat" or "Gatherer" etc; an example of a frame in this category, to clarify it, e.g. "DUF_PartyPetFrame3_Debuff5" or "CT_RA_Member37CastFrame"; and lastly the actual time or memory value.

The units of time are milliseconds, the units of memory are kilobytes. While these values won't give you an effective measure of, for example, the percentage of processor time each mod is using, it will give you a good relative scale. e.g. if one mod is using 5 times more memory than any other mod, there might be a problem with it.