Help, mikrotik slow and losing ping

hello people, i need help

I’ve a mikrotik 2.9.27 on:

motherboard asus psv800-mx
MEM 1 GB DDR
Proc Celeron D 2.13
HD MAXTOR IDE 80 GB
Device PCI 3com 3c59x (NAT)
Device PCI RTL 8139D (ISP)
Device onboard VIA Rhine I/II (NAT)

Conf:

Queues Simple
Queues Tree (cache full and p2p controll)
Webproxy active (transparent proxy)
3 NAT

Clients:
59 clients on NAT
768 KB download (ISP)
768 KB upload (ISP)

The problem is when I access internet on NAT, I have loss of packets and ping, my internet connection is slow.

What’s problem here?

Thanks

Waiting …

I’ve a mikrotik 2.9.27 on:

Upgrade your ROS, stop using an illegal copy.