OnePlus 3 tweak helps apps take better advantage of its massive 6GB of RAM29
The fix is a wee bit technical but if you're comfortable editing your phone's build.prop file, a configuration file that includes a ton of system settings. Buried in there you'll find a line reading ro.sys.fw.bg_apps_limit=20, and by changing that 20 to a higher number (both 36 and 42 have been suggested as good alternatives, with each showing similar performance gains), Android will allow a greater number of apps to run in the background before it starts pruning others.
Problem is, though, this might not be the best solution when we also consider possible trade-offs, chief among them battery life.
On Twitter early this morning, OnePlus co-founder Carl Pei defended the memory management system on the OnePlus 3, writing that it's set up to benefit battery life while balance performance for what should ultimately be “the best user experience.”
While supporting the way the phone's currently configured, Pei also made it clear that OnePlus has no issue with people who would like to set up their phones differently, and third-party ROM devs are welcome to fiddle with memory settings to their hearts' content.
source: XDA-Developers, Carl Pei (Twitter)