Its not my PC. I have 3 pc's TOP SPEC.

@Cathal-Farrelly Hi, what are your PC specs?

I have 3 pc's TOP SPEC.

It would be great if you could detail the specs for those computers.

Can you paste in the problem details from your crashes?

15 introduced a new decoder for AVC media. It didn't work nicely with some media and many people disabled it (change use so4compound to FALSE in internal preferences). It was refined in 16 and 17 and still had issues. By 18 it's mostly better.

What are your CPU and GPU for each machine?
What media are you using? If it's from a camera, which one? Is it from a phone? DJI? GoPro? Stability is often a combination of GPU x media.

How did I know you guys would ask my PC spec. It's not my spec. A PC I had 12 years ago runs vegas perfectly. I have 2 pc with the same spec. I had 3 editors working for me.

i wouldn't mind the crashes if I could edit in real time like I did 16 years ago.

I used to work in the computer games industry. We used sony vegas to edit our intros.No no problems going back 17 years plus.

Now I have been shooting and editing weddings for 15 years using sony vegas so I am pretty familiar with computers and tec over the years.

It's not my cameras or files either guys. All my video files are mp4.

Even when I record my video's via obs to make our youtube video playing games. All the vegas struggle for me to edit. IT HAS PUT YEARS OF TIME on top of my editing being so slow and crashing.

I HAVE 2 OF THESE

PC-1 SPEC Processor AMD Ryzen Threadripper 1950x 16 core processor 3.40 GHz

64gb ram

64 bit operating system

Graphics card GTX 1080TI BY 2

then another pc spec processor intel(r) xeon9r0 cpu e5-2696 v3 2.30 ghz

RAM 64

64 bit operating system

Graphics card gtx 1080ti 11g the one above has the same 11g

The processer in this cost alone €3k when i got it.

I think we're getting somewhere- it's the media x NVIDIA GPU x older versions of Vegas most likely.

I've used VP 12 (very solid), VP 15-17 (not so solid for certain media) and 18-19 (generally no crashes).

MP4 isn't a type of media. Try pasting in MediaInfo for your captures. Instructions.
Here are some recommended OBS settings for Vegas.
https://www.vegascreativesoftware.info/us/forum/faq-what-obs-studio-settings-work-well-with-vegas-pro--109925/

Vegas works best with Intel decoders but these systems don't have that.
For your 1080 cards, install the latest NVIDIA Studio driver.

For testing issues with decoding, you can try to disable so4compound to read your media and it should work like it did back in VP 14 or earlier. Hold shift, go into preferences search for s04 and set true to false. See if it's more stable though performance may decrease.

If you have OBS files and other captures which are highly compressed, variable framerate, etc. (MediaInfo would tell us a lot here), consider re-encoding your media before bringing them into Vegas. Handbrake can do this- try the production presets. Do that and you should have crashes disappear and performance increase.

Also try the trial of VP 19 as it really does work better than older versions and is still under development (so if you find a bug they can still fix it).

Vegas 14, 15, 16, and 17 are not "Sony" products. They are also discontinued and won't be developed or updated further. So for better or for worse, there is nothing to be gained by making comparisons. I agree that VP14 is stable, and I keep it installed.

Welcome to the user forum for Vegas Pro. We are here to help you if you want help with a particular problem. In order to do so, in addition to a detailed description of a specific issue that someone can reproduce, we need all of the following information in order to eliminate irrelevant responses:

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

On the other hand, if you just want to vent, the place to do it is here:

https://www.vegascreativesoftware.info/us/offtopic-forum/

As for your experiences across over 17 years+, just set your VEGAS porject not bigger/higher than 1280*720/29.97fps and use source materials equal to or smaller than fullHD in DV-AVI, Mpeg2 or any MP4 that since 17years not changed, then you can get very SOLID editing. In any version of VEGAS. 

As for our lessons over the time, we struggle always with video resolution, its new codecs, advanced hardware etc. 
Be frankly to say, I never have had a SOLID workflow in VEGAS, but I know why. 
1988 I bought my 1st computer with 2 floppy disk drives, cost: 6500DM (Deutsche Mark). 

The problem: 
Open your sight and try to find out what's wrong or why not solid.
That processor in cost of €3k is like my 1st computer which I thrown away in late last cnetury. 
Pardon me, don't misunderstand I'm teaching.