SQLite only allows one writer at a time, so depending on your access pattern that might be an issue, but if your site is getting a million requests a day then y

SQLite only allows one writer at a time, so depending on your access pattern that might be an issue, but if your site is getting a million requests a day then your only processing an average of 11.5 requests per second, and what percentage of them are writes? Front your app with varnish, nginx (w/cache), or cloudflare and absorb some additional load. Though as far as I can tell www.sqlite.com is running on a single linode instance with no fancy hacks.