fulvia,
both as VSTi in Reaper and in standalone, really good loading speeds and well within bounds for CPU here. No changes recently.
I'd first suggest re-scanning plugins in Reaper settings - esp. if you recently updated Pianoteq. (short version: Reaper and many other DAWs keep a 'cache' rather than 'latest' info on all plugins - it's not a Pianoteq thing).
(In Reaper, Cntrl P - or goto options/preferences/VST and click the "Clear cache/re-scan" or "Re-scan" button - and just eyeball the path to see it's OK etc.)
There are other settings there in Reaper pertaining to plugins - some may be rare but suit your hardware etc. or you may notice a checkbox you know is worth clicking there also.
There are swathes of documents old and new in a web search for something like "setting my PC for audio work" on other even recent threads, and of course elsewhere online. Hope this helps yourself or other readers who may not have much exposure to all this.
Just post a little more info if you need more help fulvia - There may be more than a few things which you could alter to get surprisingly better performance and more than a few people here may have some recent experience or solid ideas based on any new info you supply.
Pianoteq Studio Bundle (Pro plus all instruments) - Kawai MP11 digital piano - Yamaha HS8 monitors