Windows Explorer icons in TortoiseSVN take a long time to refresh to correct state

As stated in the FAQ: try running a cleanup.

You can try this:

TortoiseSVN -> Settings -> Icon Overlay, set Status Cache to 'Shell' instead of 'Default'

Ref. to the Help.

Shell Caching is done directly inside the shell extension DLL file, but only for the currently visible folder. Each time you navigate to another folder, the status information is fetched again.

Advantage: needs only very little memory (around 1 MB of RAM) and can show the status in real time.

Disadvantage: Since only one folder is cached, the overlays don't show the status recursively. For big working copies, it can take more time to show a folder in explorer than with the default cache. Also the mime-type column is not available.

I posted a similar answer here but to save you the trouble of opening the link I will quote it here:

I'm not sure if this is exactly related to your issue but I have found TortoiseSVN can sometimes be quite slow when dealing with repositories that have a lot of files in them. This manifests itself in the tsvncache.exe process taking up a lot of memory. The tsvncache.exe process scans files and folders and associates the familiar icons with them to denote changed/ignored etc. files.

A fix for this is to tell Tortoise SVN to only cache the folders you are working in and ignore the others. To do this, right-click your project folder and select TortoiseSVN->Settings->Icon Overlays. I have Exclude paths set to c:* and d:* (basically ignore all fixed drives) and Include paths set to my projects folder.