I have the same issue. I'm using Lightroom Classic release 8.3.1. I have a Windows 10 OS, 48 GB or ram, 4GB vram using a GeForce 950 Graphics card. Use of graphics processor is turned off.
I never had this problem until the latest release of Lightroom Classic - and I only had 16 GB of ram. I just added 32 GB of ram thinking that was my problem, especially as I often run Photoshop at the same time. Even with 48 GB of ram I get the delays described by juliankahlil.