WiFi Latency Issue

about every 8-15 seconds, for about a second at a time, my ping will shoot up while using soulseek connected to wifi. wired connection is fine.

what do you ping (local or remote) and what's high for U?
When you ping your WLAN AP/Router it's local and should be in about 10ms range (WLAN Pakets are different than LAN pakets) while LAN should be below 1ms. When you ping remote machines (e.g. google.com) it depends how you are connected to your ISP. DSL has a typ lag of 40ms. My UMTS up to 100ms. Long range pings (from Europe to Southern America) could take 400ms+ additional, while HighAvailable Servers like google took less than 5-10ms.
So there's a big range what could happens and from what reason. WLAN depends as well how free your channel is, on what frequency you work and how many senders are in your range (~200m) who could disturb your channel(s).
I'm quite an expert for (global) networks, but with it comes a lot of variables to debug...