After years of struggling with severe stuttering, hitching, freezes, etc., etc., and feeling like I'm playing with super high ping most of the time in UT4 I think I've finally found a fix for it.
I've tried multiple hardware upgrades, multiple fresh OS installs and countless tweaks over the years. Many things helped a bit but nothing ever got rid of it entirely. Then last night while researching the issue on Google I ran across a newer ini tweak I'd never heard of before that many players in multiple different UE4 games attribute to fixing similar issues for them.
And it worked for me in UT4 too.
To try the tweak yourself just open your Engine.ini file (found in Documents\UnrealTournament\Saved\Config\WindowsNoEditor) and add the following to it: