It may also be isolated to how well integrated your router is as well.

My main router is pretty well integrated and I'm getting clearnet level responsiveness when browsing the I2P site.

I switched to my router that's in a different continent that's been up less than a day and it's noticeably slower, though not annoyingly so.

I want to make sure it's available and responsive regardless of the network and access method so let me know if it continues.