From our production stats, a median screenshots capture is 5.7s. Browser-use bills per minute, not per millisecond like lambda does. As is, it's around 2x more expensive than Lambda for our use-case.
We run a screenshot API (ApiFlash) with Chromium packaged in an AWS Lambda container image instead of Firecracker on EC2. AWS Lambda gives you the isolation and autoscaling for free which is ideal for spiky stateless work like screenshots. I believe we get mostly the same benefits compared to browser-use solution but with a much much simpler architecture. The tradeoff is the AWS lambda cold starts, but in practice sequential AWS Lambda invocations actually reuse a hot function. As a result, with a large enough volume, spikes are smoothed and cold starts are not that frequent.