Opening multiple wav files VERY slow

I’ve been noticing a problem with WL Pro 11.2 lately with opening 2 more files. I typically record our band’s rehearsals/performances on my Zoom H5. I use 48khz/24 bit wav file format. After transferring these files to my MacPro (late 2013). I select both files and opening them both with WL 11.2. Both filenames are shown on the tabs of the audio editor but I can only select the first one for the initial 30-40 seconds. After that I can select either one for editing. I tried doing one file at a time but the same slowness occurs. If I close the files then open them both again, the files load quickly and can be edited right away. As a work-around, if I click on a non-WL window (e.g. Finder) then click on WL again, I can select either file’s tab to edit with any delay.
I think this has been happening since WL11 but I’m not sure.