Timeline is lagging while playing the footage and i can't view video properly

What are the complete computer specs, including hard drives (how many, what kind, what is on each, what capacity, and how full)?

If NVIDIA graphics, make sure to use the latest Studio Driver from NVIDIA (NOT the Game Driver).

Please use the free MediaInfo and post a screenshot of the properties of your media in tree view:
https://mediaarea.net/en/MediaInfo

Many users are having issues with VFR. If the file is variable frame rate, use Handbrake to convert to constant frame rate before importing into Premiere Pro:
https://handbrake.fr/downloads.php
Here is a tutorial:
https://www.youtube.com/watch?time_continue=34&v=xlvxgVREX-Y

Shutter Encoder may also be used to convert to Constant Frame Rate:
https://www.shutterencoder.com/en/

Check the Audio Hardware Preferences. Default Audio Input should be set to No Input.

in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.

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