Thanks for letting me know! 0.13.8 should be much faster for redirects now, as it's done on the extension side, rather than the content script :) The delay isn't entirely gone, as it still needs to perform a HEAD/GET request to ensure the larger image exists, but the userscript's overhead shouldn't be relevant for redirects now.

There's still more work to be done performance-wise, but I hope to be able to address some parts of them soon (others will require a rewrite of currently >55,000 lines of code, so, they will probably come a little less soon haha). I've tracked the issue here: https://github.com/qsniyg/maxurl/issues/294

Let me know if you have any other problems :)