Obviously larger files take longer to load, but this is not a difference between TiddlyWiki and “regular websites”.
Most of my TiddlyWikis are way smaller than 25MB, including serious workhorse wikis packed with content (with or without pointing to images which are hosted elsewhere). An empty TiddlyWiki is under 2MB. In comparison to one high-resolution photo (let alone video!), and the size of TiddlyWiki’s core immediately looks negligible.
If you say more about your situation, you may find even better advice.
For example, this may or may not appeal to your use-case, but here’s a fantastically convenient solution: I regularly work with TiddlyHost on sites that involve a workflow of ongoing frequent modification. For sites that aren’t about TiddlyWiki, I enable a read-only mode that appears for anyone other than me ( = anyone accessing a public site but without being logged in via my own account at TiddlyHost). So I get the best of both worlds: convenient editing whenever I load the site myself, and web-publication of those same files (in read-only format) with zero conversion effort.