Change site SUB-URL from .co.za to .com

Hi there.

Our main site is consuming a lot of traffic, CPU and Entry Processes causing some issues from time to time.

I recently also started a forum from a sub-domain on the same domain that is also consuming a lot of traffic, CPU and Entry processes, that just add to my problems.

I believe that both sites (main site and all the sub-domains) make use of the same CPU and Entry Processes, set on the server. We just upgraded to our own cloud server that will apparently eliminate this.

-I was thinking of splitting “site.co.za” and the “forum.site.com” that both use different resources – also for future use. (Already registered both domain extentions).
-Made use of plugin to move all the content as is from the one site to the other that works perfectly.

Problem is that it moves the pages with the same structure, but it don’t fix the links in the pages.

Is there any plugin that I can install on the old site to direct any traffic from the old page to the correct domain (Only the domain extension that is changing)