Linksys Wireless Router :: E3200 Lag Spikes And Unstable Network

I recently replaced my old WRT54G router with a E3200 router.
 
Unfortunately, ever since my wireless network is a lot more unstable than before. I very often experience serious lag spikes and drops in speed. Very often I experience serious lag for a couple of seconds after which everything returns to normal. I notice this the most in online gaming, but it is also noticeable while browsing the web. When downloading large files (e.g. steam games), the download speed also seems to suffer from this by dropping every now and then.
 
There are no connection drops however. And it only seems to affect the wireless network.
 
I have configured the E3200 router manually using the Web UI and is has been configured exactly the same as my WRT54G: i.e. only 2.4GHz band enabled with b/g/n, WPA2 security, MAC filtering on, no throtling/parental control/port forwarding, UPnP disabled. The E3200 is in the exact same place as the the WRT54G was.
 
Things I have done so far for troubleshooting: I used inSSIDer to monitor the wireless network and it's signal strength seems about the same as the WRT54G. I changed channels for best signal strength (there is only one other wifi network that seems to be configured as a dual channel N network; 3 other networks with very low signal strength) and have tried every channel.
 
I updated the fimware to the latest version (Ver.1.0.04 (Build 1)) and did a factory reset and power cycle afterwards.
 
I noticed that switching channels can account for 5-10Mbps differences in internet speed. Something I never noticed with the WRT54G. The lag spikes occur more often on some channels than on others. This seems not related to the speeds I get on the channel.
 
I really can't imagine that a router marketed as High Peformance router with superior speed and superior range is less stable than my old WRT54G router.
 
Is there something I can do to improve stability of this router?