Persistent srorage size

Chrome reports Persistent Storage for secure.runescape as 2.9GB. Is this size based on anything or is it a set size for everyone?

I think the Persistent Storage is too low based on this repeated experience:
1. Teleport to Area A, wait for it to finish loading (Build State 100%)
2. Teleport to Area B, wait for it to finish loading (Build State 100%)
3. Teleport back to Area A, wait for it to finish loading (Build State 100%)

Step 3 takes just as long as it did the first time in Step 1. It appears that Area A was evicted from the Persistent Storage cache. The reported Disk cache never seems to exceed ~3030MB and when it does, it’s very brief and then reduces back to ~3000MB.

Can any developers comment on this?