Current iPads have 1GB of RAM. They also constantly evict background applications and even backgrounded tabs in the web browser. Switching browser tabs on iOS is always a gamble as to whether it'll reload the page or not. This makes it impossible to, for example, write a comment in one tab while referencing some material in a different one with any kind of reliability.
iOS is extremely memory efficient but it comes at a cost which can be quite high for some.
