Best Practice / Approach Performance Factoring by identifying Plugins

Dear Community Developers,

I have noticed that the elgg installation starts with quite a substantial speed and performance without having to

1. enable memcache, apc, apcu, opcache, redis (the supported ones). 

2. Twerking the data root and db caching

//$CONFIG->cacheroot = "";
//$CONFIG->dataroot = "";
//$CONFIG->simplecache_enabled = true;

3. Having Caching Compression, Symbolic Link disabled

4. Even not properly syncing PHP memory values with .htaccess.

What I have noticed that as I add plugins, the Elgg struggles to function properly with all of the above disabled and often resorts to Error 500 or 550 (forgot) displaying Performance Capacity issue. 

The point is I have identified few plugins that causes this problem. Without those plugins Elgg with all of the above disable functions well and should work at the speed of sound and smooth like silk when above disabled resources enabled and tweaked. 

So, the questions are:
1. is there a way to identify which plugin is taking up memory resources and causing high CPU usage?
2. What would be the best practice to factor for performance (when it comes to plugins).

Please note, I have Vroom Plugin enabled. 

Also there are other Performance resources like (but not supported) 

(Node.js, Varnish, "Supervisor" for background processes (instance, you can set up a real-time bidirectional connection between a web client and a server over the TCP-based WebSocket protocol.) ) Furthermore,   Elgg 2.3 with PHP 7.2 (this version of PHP speeds up Elgg  so well it feel like a rocket), but  unfortunately the Memcache  doesn't function unless otherwise downgraded to PHP 5.6, and even with 5.6 the redis wouldn't work or function although I think the scope is declared for Redis. 

Does Elgg Core have plans to address is Core issue?