Thanks for the response, but no effect unfortunately.

Pressing F5 to refresh contents of any folder, or bringing up 'save as' dialog box still causes File Explorer/explorer.exe to freeze for 5-10 seconds. Verified OneDrive was uninstalled, removed or disconnected any shared folders or drives, unpinned all 'Quick access' folders. Uninstalled a lot of third party programs one-by-one to see if that had any effect. No idea what's causing this.