virtualbox – Unexpected vm behaviours

I recently started using ubuntu in a vm with windows as a host, but facing countless unexpected behaviour mentioning some below

Chopping of audio while playing some videos on firefox
When i open some application the window of the same keep clipping with constant black screen for indefinite time
Continous beep type sound from ubuntu after using it for a while

I did installed the guest addition provided neccessary resource based on my knowledge
8gb Ram, 128Mb Video memory , 4 cores of Cpu, 3d acceleration

top – 15:28:16 up 30 min, 1 user, load average: 0.84, 0.90, 0.64
Tasks: 256 total, 1 running, 255 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.9 us, 3.1 sy, 0.5 ni, 94.2 id, 0.1 wa, 0.0 hi, 0.2 si, 0.0 st
MiB Mem : 7941.4 total, 3457.2 free, 2811.8 used, 2141.6 buff/cache
MiB Swap: 4096.0 total, 4096.0 free, 0.0 used. 5129.6 avail Mem

It doesn’t seems to be a issue with the resources so what can be the possible issue and fixes