Since last week I have a new PC (Dell XPS). Lightroom Classic is very slow in converting the CR3 RAW files into TIFF before sending those to Photoshop. The same slow action can be seen when calling any of the Topaz plugins. Any setting I should/could check?
A comment on your post-
LrC does not convert a raw file to a TIFF (or PSD) BEFORE sending to Photoshop (Specifically Photoshop!).
ACR does render a visible image in Ps.
Until you [Save] the image from Ps only then is a TIFF created.
(If you [Close] the Ps document, without saving, then no TIFF is created or saved.)