Footage lagging project, working with different types of files and converting HDR10+ to sdr

[DivineKataroshie]

Hello! so I am currently working on:

Adobe Premiere 13.1

My specs: https://www.userbenchmark.com/UserRun/36068839

Windows 10

and after adding my files to a new sequence I noticed this type of glitch started happening (video):

I encountered various performance issues and lags many times, so first I reseted preferences and workspace to default, updated my graphics drivers, and disabled audio input without much succes.

The person who sent me the footage told me He used Samsung Galaxy s10+ and one of the updates enabled HDR10+ which is currently unsuported by most monitors and the footage looks gray and muddy when viewing on PC, so he used this method with mmpeg to convert it to normal SRD: https://www.maxvergelli.com/how-to-convert-hdr10-videos-to-sdr-for-non-hdr-devices/ And apparently it makes premiere and even MediaPlayerClassic lag. So it's definetly the mp4 file itself.

So my questions are:

A) Is there any other method to convert it so that it will not cause this types of audio/video glitches and lags?

B) I encountered various types of issues related to files having different codecs, resolution, FPS, format, etc. Usually I create new project, import my files and move one of them to create a new sequence and start working. Usually somewhere in the middle of editing premiere starts to act weirdly because of all this different footage. Is there a secret of working with files from different cameras, screen recordings from OBS, etc? do professionals usually convert the footage first? or how to make this workflow more consistent and smoother? 

[Bruce Bullis]

Any reason you're testing with a two-year-old version of the application, rather than current?

[DivineKataroshie]

Actually yes! A lot of autohotkey scripts I created for transitions, color correcting, and audio effects just bugged and lagged so much on newer versions of premiere, and the program crashed at least 2 times a day. Where this version works flawlessly! 

[Bruce Bullis]

I'm glad it works, and...it's not terribly useful to make performance comparisons between current and obsolete versions of PPro...

[Warren Heaton]

Treat your edit like it's for a feature length documentary.  That is, conform all of your source to source footage that's good for editing. 

Specific to what you're doing, I'd opt for source footage that's all ProRes 422 LT with Video Previews in the Sequence settings also set to ProRes 422 LT.

Any of the CODECs that work with Smart Rendering in Premiere Pro are good for editing (https://helpx.adobe.com/premiere-pro/using/smart-rendering.html), but ProRes 422 LT fits the workflow that you've described very well.