Microsoft has begun seeding a new update for Windows 10 Mobile. The firmware's build number is 14267 and it tweaks the multi-tasking performance on mid and high-end Lumia phones. With this new update, Microsoft has doubled the number of apps Windows 10 Mobile can keep alive in the RAM. The number is now 16, up from 8 apps previously. This will allow high RAM Lumias to switch faster between different apps. Doubling the app limit won't drain the battery more unless the apps kept alive aren't doing additional background activity such as downloading, syncing, navigation, etc. The multi-tasking on the affordable Lumia smartphones with 1GB RAM or less won't be affected by this new update. Source ...
Source: http://www.gsmarena.com/microsoft_seeds_a_new_update_for_windows_10_mobile_tweaks_multitasking-news-16816.php