You have made setting changes that affect the rewrite rules for all blogs. Click below to rebuild th

Hello,
How long will this process "You have made setting changes that affect the rewrite rules for all blogs. Click below to rebuild the rewrite rules for all sites" take? I've got about 3500 blogs and growing.

Each time I visit my network settings for the Ultimate Translation settings I see the above message and although the translation widget shows in the sidebar, I can not see that any page or post has been translated.

When looking at individual post of pages in the dashboard, it looks like translation is complete.

Thanks for your help.
R.