Improve PageSpeed to 80+

[willhennessy]

As part of our SEO optimization, let's improve our PageSpeed score to 80 or higher.

.org: https://developers.google.com/speed/pagespeed/insights/?url=uniswap.org
app: https://developers.google.com/speed/pagespeed/insights/?url=http%3A%2F%2Fapp.uniswap.org%2F

[zzmp]

This should be resolved with #2212 and #1944.
This does not resolve it for .org, but that issue is filed separately under Uniswap/org-v1#294.