iPad Pro 12.9 generation 2 slow touchscreen
Slow response touchscreen
iPad Pro 12.9-inch, 2nd Gen, Wi-Fi, Cell
This is a well known, long standing issue in these iPad support communities with still NO resolution from Apple after nearly 3 years!
I strongly suggest you contact Apple support via the contact support link located at the upper right hand corner of every Webpage of these Apple support communities OR by installing and using the Apple Support app found in the iOS App Store.
Tap the iOS App Store link below.
https://apps.apple.com/us/app/apple-support/id1130498044
If you can, if no real resolution of this from initial Apple support employees, be courteous, but I urge you to keep pushing this issue up higher ranks of Apple support personnel.
This has been a long standing issue that has still not been figured out or solved by Apple and it needs to be pushed up to higher level tiers of much higher level, engineering level Apple support personnel.
Best of Luck to You!