Does US East Coast versus West Coast hosting matter?
The short answer
It can matter, especially when requests must reach your application server. Choose using your visitors’ locations and measured response times, rather than assuming a fixed coast-to-coast delay.
In more detail
Start with where your visitors are concentrated. For an East Coast audience, include an eastern region in your test; for a West Coast audience, include a western region. Amazon Lightsail offers Northern Virginia and Ohio in the east, and Oregon in the west.
Compare the same application and plan with the same cache settings. Test real page requests from the cities and networks that matter to your business, including busy periods. Record response times and failures instead of relying on an assumed millisecond difference between coasts.
For a nationwide audience, compare the overall experience rather than optimizing for only one city. A CDN may help cacheable content, while dynamic pages still need application and database performance checks. Balance any improvement against cost, reliability and the work required to move.