WoW's performance is highly dependent on CPU usage rather than memory usage.

Memory usage for most computers will not really affect your game's performance but CPU usage will.

This addon helps track addon CPU usage so that you can analyze and optimize your addon setup.

This addon now automatically turns off WoW's AddOn CPU profiling recently added in 11.1.

How to use:

This is how I recommend using this addon:

1. /ecp on
2. Do a raid boss
3. Click "Yes" in the pop-up window
4. /ecp show

Commands:

/ecp - display the list of commands in chat
/ecp on - turn on CPU profiling
/ecp off - turn off CPU profiling
/ecp start - start manual profiling logging
/ecp stop - stop profiling logging
/ecp show - display logged data
/ecp live - display live CPU usage data
/ecp delete - delete saved logs

Automation:

In raid, if CPU profiling is enabled, the addon will automatically log your CPU information on pull. At the end of the encounter the addon will automatically stop logging and a popup will appear asking you if you want to disable CPU profiling.

Using this automation is how I recommend using this addon.

CPU profiling can be taxing on your system. For this reason the addon will always automatically ask you if you want to turn it off in case you forget that it's on.

You can then use: /ecp show
to display the most recent CPU profiling log.

I do not think that live tracking is very useful unless you are developing an addon.

WeakAuras:

WAs will likely be your highest usage addon (unless you use ElvUI in which case ElvUI + ElvUI Libraries will be your highest usage).
WA has their own profiler. Here are the commands to profile your WAs:

/wa pstart - use this before pulling a boss / starting a dungeon
/wa pstop - use this after encounter / dungeon
/wa pprint - this will display all of the information

I recommend reconsidering everything that appears red in the list. Even though some WAs may appear red, remember to look at their runtime: if the aura is far down the list then even though it is not a very optimal WA, it is running for a very minimal amount of time. WAs at the top of your list are the biggest culprits.

Command and Functionality Details:

/ecp on - This turns on WoW's built-in CPU profiler.
/ecp off - This turns off WoW's built-in CPU profiler.
/ecp start - This starts logging the data the CPU profiler is generating.
/ecp stop - This stops logging the data the CPU profiler is generating and saves the log.
/ecp show - This opens a frame in-game where you can analyze the data that was logged. There is a drop-down menu for you to select which log you want to look at. By default the frame will display the most recent log. The export button will open a new frame which will display the current log in an exportable form. Using this command again will open a new frame. This can be useful if you want to compare 2 or more logs in game without having to export anything.
/ecp live - This will open a frame that tracks CPU usage data live. It updates every 2 seconds. It will only show the current CPU usage of each addon at the snapshot time.
/ecp delete - This will open a frame that lists your saved logs and allows you to delete any logs that you do not want to keep.

Ecfigia's CPU AddOn Usage Profiler