Intel Hexcore i7

???? Can you can give more info? Because

six core i7

That says nothing about the build and about the power ( also memory) of that processor and because most of loading has to be done through the processor and the amount of memory it uses, that is very important.
I cannot see if your processor has the minimum specs for VP17 last build.
For decoding the used sourcefiles a little help is given by the decode method @Grazie mentioned.
What are your used sourcefiles and more important: do they match your projectproperties to overcome extra decoding and reading problems?
Look here under C to provide the needed info: https://www.vegascreativesoftware.info/us/forum/important-information-required-to-help-you--110457/

ok i will check, decoding, encoding, effecs, playback and editing works fine

sourcefiles are:

Panasonic GH5 10-bit 422 AVC footage 1080 p 25fps

project settings same as sourcefiles

it is only loading the project at startup which takes time

thank you

It must be a long project, maybe it is easier at the end to load several "nested vegs" that will together make your whole project?

Those "nested vegs" do have proxies if you load them as vegs, and those nested together proxies are easier to build.

Your footage is well-known as a slow performer. Build a proxy