tile server image generation speed

i set up a map server on ubuntu 18.4 the vm have 8 core cpu and also 16 gig of ram i just imported great Britain pbf data

but the map generation speed is very low

some time it need 10-15 seconds for generate tiles and also some time it dont create any thing due to timeouterror this is a part of pgsql configs

lbmap@tracker-map:~$ grep ^VmPeak /proc/16364/status
VmPeak:  4492940 kB
lbmap@tracker-map:~$ cat /proc/meminfo | grep -i huge
AnonHugePages:         0 kB
ShmemHugePages:        0 kB
HugePages_Total:    7570
HugePages_Free:     5465
HugePages_Rsvd:        4
HugePages_Surp:        0
Hugepagesize:       2048 kB

how can i get a better performance?!