Many thanks, @msmcleod, for this extra pointer. I found that Kontakt did this automatically when using the Batch function step. I will know, now, to double check this.
Until recently I was mainly using Spitfire dedicated plugins (e.g. Originals, a smaller Abbey Road One library). Separate instances for each instrument in my small projects (only about 5 VST tracks, an audio track I'm forking, then later some bounced audio tracks, no FX etc) were working fine on my system (Acer Nitro i5 quad core, 8 Gb RAM, external 2TB SSD, Focusrite 4i4 Gen 3, Win10). But now I'm experimenting with bigger Kontakt libraries, and combining more instruments etc, the above instructions will become increasingly useful I think. So much to learn!?