iPhone 5 Notifications Center Lag

Always thought iOS is smooth but I keep encountering this lag that is reproducible and happens quite often. When a notification comes in about the time I am swiping down the Notifications Center, it stutters and lags pretty badly. This also happens quite notably when I jump to an email/message via Notifications Center, and the notification is being removed from the Notifications Center.

It sometimes also affect swiping between home screens and the multitasking bar.

It's fine after a reset of the phone, but it quickly exhibits such behaviour again.

Anyone encountering such an issue? I'm on the latest 6.1.2 software version.