Performance improvements on TreeTable

[qad84]

Hi,

The DOM event take very long time when expand/collapse node.

[ ] bug report => Search github for a similar issue or PR before submitting
[x ] feature request => Please check if request is not on the roadmap already https://github.com/primefaces/primeng/wiki/Roadmap
[ ] support request => Please do not submit support request here, instead see http://forum.primefaces.org/viewforum.php?f=35

sample stackblitz
https://angular-primeng-treeview-demo-p5yahy.stackblitz.io

**Current behavior**
This is sample demo: 
https://angular-primeng-treeview-demo-p5yahy.stackblitz.io 
When expand node, there is DOM event (click) takes a long time (in IE/Edge) 
This event will execute many removeChild() and insertBefore() functions. 
In case we have a lot of nodes then it will take minutes just for expand/ collapse node

I also use lazy load for child nodes 

**Expected behavior**
Improve the performance of DOM event on expand/collapse event.

**What is the motivation / use case for changing the behavior?**
<!-- Describe the motivation or the concrete use case -->

**Please tell us about your environment:**
<!-- Operating system, IDE, package manager, HTTP server, ... -->

* **Angular version:** 
6.1.x

* **PrimeNG version:** ^6.1.2

* **Browser:** IE & Edge
 
* **Node (for AoT issues):** `node --version` =   v8.11.3

[qad84]

Hello @cagataycivici,

Could you please check it again?
This issue still happen in my example:
https://angular-primeng-treeview-demo-akjnct.stackblitz.io

It is still take 1-2s to expand/collapse in IE and Edge.

Many thanks

[keval101]

@cagataycivici,

I Have checked it with only 200rows but it takes 1-2s for expand/collapse.

browser: Chrome