Setting Up Wired And Wireless Network, One Computer Is Very Slow

OK, so upgrading my parent's wireless. They have cable, 2 wired computers, one wireless laptop. I put in an older Linksys flashed to Tomato, but it is pretty slow compared to the newer wireless standards. Going to get them a new wireless router like the one I have. I have one wired, one wireless, same cable company for internet.

My laptop gets around 45 down, 11 up, my desktop around 60 down, 12 up using SpeedOf.Me to test. At the folks, one wired computer gets very similar to mine, the other wired one gets 6 down, 12 up. (all Mbps) The one in question has a latency of over 300, while even my iPhone has 69 latency.

So, long story short, what usually causes such high latency? Will replace the wireless router at their house Tuesday, and of course test the cables, but their laptop is way faster on the wireless router than the wired one is... So, I don't suspect an issue with the Cat5.

Never seen upload higher than download. Weird.

 

Replaced the wireless router. Wireless is faster (they had a pretty old one). That one computer is still backwards, upload twice the download... I forgot to change the cable going from new router to that computer, I suspect that may be the issue. That, or a funky network card.

 

Looks like the Cat5 from the router to that computer was the issue. Swapped it out, and while it is not super fast, download is faster than upload, plenty of speed for what it is used for.