Performance issues with multiple instances (massive lag and app freezes)

Check version

• I'm running the latest version of Path of Building and I've verified this by checking the changelog

Check for duplicates

• I've checked for duplicate issues by using the search function of the issue tracker

What is the expected behaviour/value?

• The app should not start lagging and freeze like crazy when you open a second instance (otherwise prevent it).
• It should ideally share resources with the 1st one (looks fine, although it a bit heavy on RAM ~400mb each).
• I should be able to search for a gem in the skills menu without a 3 seconds freeze (not responding).
• I should be able to select / unselect nodes on the tree without lag or freezes

What is the actual behaviour/value?

When two instances of PoB are running :

• Selecting / unselecting a node (even worst when pathfinding comes up for mulitple nodes) it lag massively and often freezes for 1-2 seconds
• Searching for a gem in the Skills menu should not freeze the app for 3+ seconds
• Selecting an item in the dropdown in the Items menu should not freeze or lag the app
• Creating a new item in the Items menu, should not freeze the app for 1 second after clicking save

Seems like PoB is re-calculating / doing backend stuff on the UI thread most of the time, which cause massive lag and freeze, with a medium / full size tree.

How to reproduce the issue

After opening one (or both) the following PoB codes below in two instances of PoB :

• Select / unselect nodes in the Tree menu (should notice lag or freeze)
• Search for a gem in the dropdown of the Skills menu (should notice freeze)
• Try changing the select item in one slot of the Item menu (should notice lag or freeze)

Character build code

#1 is from a build guide : https://pastebin.com/w0krs09Q
#2 is from one of my character's profile : https://pastebin.com/Eg6AtanZ

But, it lag with any medium / full size trees I've used.

Screenshots

No response

Inizia riproducendo i blocchi con due istanze di Path of Building e i codici PoB forniti, concentrandoti sui menu Tree, Skills e Items. Confronta la selezione dei nodi, le ricerche delle gemme, la selezione degli oggetti e la creazione degli oggetti tra una e due istanze; il lavoro è completo quando queste interazioni non causano più il rallentamento o i blocchi segnalati.