I have a low end phone with 4 Gigs of ram and it was working fine until i upgraded to the latest android version and now i can only pretty much run 1 applicatio

I have a low end phone with 4 Gigs of ram and it was working fine until i upgraded to the latest android version and now i can only pretty much run 1 application a time. I can switch between apps but they loose state and reload on switch. I swear to god when i get a new phone, i'll never run rom updates...