Client caches are a thing, so this is most relevant for cold-start customers. In that case PeakSlab’s download size is an advantage.
Fwiw LocalStorage is a SQLite db on most browsers, with a kv api. It’s be interesting to have the actual API available.
Even on warm start PeakSlab is twice as fast. It's not just download size, it's execution speed, zero copy, database decompression, etc.
That's why PeakSlab is written in c, because what's faster than casting the whole database to a struct? ;-P