Trimming UI takes a long time to appear

[merapi]

Bug Description

It takes a while to show the trimming UI, sometimes it takes more time to show the trimming UI than to process the video - so that might be an even bigger issue than the final processing.
Here are the results:

Video length	Computer	Time to process (insert)	Trim UI wait time
10s	8yo 4c laptop	24s	3s
10s	M1	7s	3s
60s	8yo 4c laptop	80s	20s
60s	M1	18s	54s
120s	8yo 4c laptop	150s	43s
120s	M1	25s	110s

Expected Behaviour

Trimming UI needs to show instantly.

Steps to Reproduce

Try on 1min+ video.

Screenshots

Additional Context

• Plugin Version:
• WordPress Version:
• Operating System:
• Browser:

[felipebochehin87]

Tested using PR #12001.

Tested using my PC:

Windows 10
Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz 2.21 GHz
RAM 16 GB

And also my MacBook

macOS Monterey
Processor 2.6 GHz 6-Core Inter Core i7
Memory 16 GB 2667 MHz DDR4

Safari, Firefox, Chrome.