Along lines of my recent question, here's an article with a set of steps to try to, possibly, sort out issues with file explorer being laggy, or unresponsive - not sure it really relates to it taking a while to launch, but, have run through these steps in any case:
https://helpdeskgeek.com/windows-10/how-to-fix-windows-10-file-explorer-not-responding/ Effectively - sort of explaining each step, and the reason for considering it, they talk about modifying windows display layout, killing file explorer process - think that one is least relevant in my context - running system file check, which I did, with no bad results, clearing file explorer history cache,which might very well be relevant, checking video driver update status, windows update check, check for viruses and malware, and run system memory diagnostics.
In other words, while not necessarily relevant, some of these steps/processes might be something to keep in mind in any case in terms of performance, reliability, etc. - hence why I am sharing it.
Stay well
Jacob Kruger
+2782 413 4791
Skype: BlindZA
"...resistance is futile...but, acceptance is versatile..."