This must be fixed long-term by segregating browser capabilities into tiers that are clearly visible to the user, and severely limiting defaults on data size, c

This must be fixed long-term by segregating browser capabilities into tiers that are clearly visible to the user, and severely limiting defaults on data size, compute time, etc. especially when your site claims to belong in the "simple web site" tier. In other words, unless the user thinks it makes sense for you to download lots of data and do complex things, you can't.