https://www.vegascreativesoftware.info/de/forum/important-information-required-to-help-you--110457/

Start with "B" and "C",
First check whether media properties and project properties match.
Ideally, when loading the first event, where Vegas Pro will automatically ask for it.

By "Jittering" I assume you mean the playback framerate is low/inconsistent? We need to know what kind of hardware you have, and what kind of media you have on your timeline.

Unfortunately VP isn't just plug and play on some systems. On my main machine, where I run everything I use, it's less stable.

On my new render-only machine, it's much better though I do have to be careful about s04 hangs (still using 17)

Give these a shot. Esp the so4 disabling, though it's more stable in 18, and make sure you're using both a clean driver install and the latest studio or pro driver for your card.

FAQ & Troubleshooting

https://www.vegascreativesoftware.info/us/forum/vegas-pro-faqs-and-troubleshooting-guides--104787/

VP instability

Try:

The recommendations in the FAQ for solutions when VP is crashing.

Disable so4compoundplug.dll if videos are AVC https://www.vegascreativesoftware.info/us/forum/avc-xavc-s-issues-in-vp15-16-try-disabling-so4compoundplug-dll--108345/

A driver cleaning http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

If you're using an Nvidia GPU make sure you're using the studio driver, not the game driver.  I've also found that the 451.48 driver is much more stable with VP than previous versions

Make sure your cache folder is clean by deleting everything in  C:\Users\<user name>\AppData\Local\VEGAS Pro\<version #> (delete everything with VP closed and use task manager to make sure it's really gone from memory). The initial startup will be kind of long after this cleaning but once it's up, restart VP again. Use task manager to make sure VP is completely gone from memory before starting it back up.

Try these tips too 

Trim your project looking for fx combinations that cause problems.  For example, Picture in Picture and Layer Dimensionality together are lethal on my machine

Disabling so4 breaks compatibility with some formats, so keep that mind when poking around in those settings.

Vegas 18.0 Build 284
 
Alienware Aurora R7
Intel Core i7-8700 CPU @ 3.20GHz  3.19 GHz
RAM: 16gb
Windows 10 Home
Version 1909
Build: 18363.1016

Video Source: Vegas Noise Texture  1980 x 1080
& Video Media Generator: Vegas Titles & Text

NVIDIA GeForce GTX 1070

Driver:  NVIDIA
8/12/2020
27.21.14.5206

Render Seems fine, only have issues when playing back timeline
When it comes to any type of transition or where tracks mix (IE Title over noise texture) the video kitters and sometimes seems like it pauses until it comes to
video that isn't changing and then it plays normally again until next transition.  

This is as basic as it gets....not even using video files yet.....only vegas generated content.

GPU Acceleration:  Tried off and Optimal NVIDIA Geforce GTX 1070

File I/O all unchecked

This is a known issue for some. I have had this since vegas 15. I have a big thread on the forum about this as well and a few tickets to support . Still no solid answer to why this happens. Fingers crossed.

Vegas 18.0 Build 284
 
Alienware Aurora R7
Intel Core i7-8700 CPU @ 3.20GHz  3.19 GHz
RAM: 16gb
Windows 10 Home
Version 1909
Build: 18363.1016

Video Source: Vegas Noise Texture  1980 x 1080
& Video Media Generator: Vegas Titles & Text

NVIDIA GeForce GTX 1070

Driver:  NVIDIA
8/12/2020
27.21.14.5206

Render Seems fine, only have issues when playing back timeline
When it comes to any type of transition or where tracks mix (IE Title over noise texture) the video kitters and sometimes seems like it pauses until it comes to
video that isn't changing and then it plays normally again until next transition.  

This is as basic as it gets....not even using video files yet.....only vegas generated content.

GPU Acceleration:  Tried off and Optimal NVIDIA Geforce GTX 1070

File I/O all unchecked

Same issue here still.

I've tried the same thing, and it works fine for me.
It is strange that in the properties of the noise texture it says "progressive scan" and in the project settings it says "upper field first".

It's a bit strange as you have a better CPU than me, i5 3570K @4GHz, but my GPU is better 1080Ti, your ram at 16GB (Vegas will only use 8GB) my RAM is 32GB (only recently upgraded but still worked well with 16GB installed) My footage is 4K Sony XAVC. I can (must use so4compound) play the time line at full best with transitions such a fade with no jitter including FX such as levels and stabilization applied to clips. I guess you can play the timeline fine if you use proxy files? V18 uses my GPU at about 20 - 30%. Also are you running an ssd for the the source drive?

I agree @andyrpsmith. His is better than mine as well; I7 3930 and gtx 1050 ti. But I too still get the same problems he has. Want to upgrade but waiting to see at this point. I had proxies do the same here as well. @Craig-Lewis have you tried proxies??

Video Source: Vegas Noise Texture  1980 x 1080
& Video Media Generator: Vegas Titles & Text

Looks to me not a sourcevideo on the timeline

File I/O all unchecked

You showed the projectproperties, are you able to show the setting Options/Preferences/File/IO?
And give also a screengrab of your loaded timeline with preview screen to maybe give you some help.

Just played a Veg project in V17 and got a few dropped frames (ssd drive) in places, no jitter but momentary loss. Played same project in V18 no dropped frames so V18 is definitely more efficient in timeline play back over V17.

@Craig-Lewis If you haven't done it already suggest you go to the Dell support site and update all their drivers...

https://www.dell.com/support/home/en-us/product-support/product/alienware-aurora-r7-desktop/drivers

Particularly the one for the uhd 630... suggest you stick with the dell-supplied driver for that and select it in Vegas file I/O if not already auto-selected in Vegas 18. You might also need to go into the Nvidia Control Panel and select Integrated Graphics as your preferred graphics processor, at least for Vegas... that allows Vegas to decide which to use for what without being overruled.

Just to confirm...

I have checked all my drivers from dell, everything seems good.

The "jittering" is actually dropping frames. Coming from black to first graphic it's a bit slow, but the last graphic adding in the timeline it comes to a halt and then skips frames that are taking too long to render.

There's no audio or other sources on the timeline.

I can render it and the output is fine.

Someone asked about proxies.....I shouldn't need any for something this basic, correct?

I tried what you did I think on my laptop from signature.
No problem, plays fluent.
Are you able to share such a small veg you made on a place where we can download it and try also that project of you?
 

No need for proxies for just the media generator but you said it happened with footage on the timeline correct? If so does it do this with proxies? I did just try your screen setup and have no problems here. I even made the clouds move. I did notice your preview is different from your project.Just starting vegas and dropping the text and the clouds on time line, shows both project and preview at 1920x1080. Did you change the preview size? Yours is 480x270. Just curious.