Can anyone tell me what is the maximum number of threads that Vegas is capable of handling?
And as well, considering basic editing, what is the number of threads at which performance usually flatlines?
32
Maybe only 16 ?
see the note in the article by Guru 3D
http://www.guru3d.com/articles-pages/intel-core-i9-9900k-processor-review,15.html
Hah crap. My CPU has 18 cores and 36 threads.
Is there a reason why it is capped ?
Not capped, just (maybe) not written to take advantage of these brand new processors. It's not "automagically" scalable you know.
How many cores Vegas uses effectively in practice is not an easy question to answer. You would need to test performance versus the "same" processor with less cores in a variety of situations. Without that testing I will guess 32 threads as this is what is shown in the Vegas 16 preferences. The Guru3D article only seems to have looked at one aspect (UHD render) and IIRC a Techgage article claimed the opposite. So who knows.
Why do people think Vegas is limited to 16 threads? I think that comes from some setting under the preferences for render threads. There are more threads the system uses for other tasks.
I have seen Vegas use over 70 threads, you can verify this under task manager by adding thread count to the columns. Windows controls how the CPU threads are utilized.
If the render engine used all the threads while rendering, your GUI would not be responsive.
The setting is in the video preferences section. 16 for Vegas 14, etc. 32 for Vegas 16.
Personally, I don't worry about the "engine" details like that; just want to know what makes it go faster :)
Ah it does utilize all, I switch the limit from 32 to 36 threads in options.
In another thread, someone posts a link to a Vegas review of processors.
So granted there are improvements in memory architecture and bandwidth, and other system elements. But the graph does basically show how more threads helps improve render times. The bottom CPU is what 4 cores/8 threads and the top is 16 cores/32 threads.
What is not shown in the review are the details on each of the test systems. I find it hard to believe that each of the processors had identical ram quantities given the vintage of some the test machines. The 2600K might have had maybe 8-16GB of ram, while the 2950x could easily have a lot more due to the amount of memory channels.