AFAIK there is server-side paging implemented in the List* API operations that the Console UI should be using so that the number of objects in a bucket should not significantly impact the webpage performance.
But who knows what design flaws lurk beneath the console.
Curious to know what you find.
Does it happen only on opening heavy buckets? or the entire S3 console? Different Browser / incognito / different machine ...dont make a difference?
I worked somewhere that a person decided using Twitter Firehose was a good idea for S3. Keyed by tweet per file.
Ended up figuring out a way to get them in batches and condense. Ended up costing about $800 per hour to fix coupled with lifecycle changes they mentioned.
You have a versioned bucket with a lot of delete markers in it. Make sure you've got a lifecycle policy to clean them up.
You don't peer into a bucket with a billion objects and ask for a complete listing, or accounting of bytes. There are tools and APIs for that.
That's what I do with my thousands of buckets and billions of files (dashboards).
Disclosure, co-founder here, we're building one of those CLIs. We started as an internal project at D2iQ (my co-founder Lukas commented further up), with tooling to collect an inventory of AWS resources and be able to search it easily.