simulate low-bandwidth or high-latency

Wireshark is a network protocol analyser and cannot generate traffic nor simulate network issues. Maybe there are items on the Tools page on the Wiki that can help.

How I can I generate network traffic and measure the peformance of the network - what tools are recommend

I can recommend jperf. Nice and easy tool for simple performance tests.

also how to simulate low-bandwidth or high-latency ?

I can recommend either wanem or trafficsqueeszer (in WAN simulator mode).

Regards
Kurt

"also how to simulate low-bandwidth or high-latency ?"

I haven't used it myself, but you might also want to look into netem.

I've had very good experience with FreeBSD's dummynet (part of their firewall).