I wouldn't have thought a lag of 25ms would cause a laggy browsing experience, 25ms is pretty fast considering it takes the human brain about 13ms to process an image. A monitor with a refresh rate of 60Hz will take 16ms to refresh an image for reference.
xDSL connections will always have a lower latency than DOCSIS due to the different ways the two technologies work, as xDSL lines are trained for stability and will only deliver the speed the stability of the line will allow, whilst DOCSIS is best effort driven. An average latency of arounf 20ms is not bad for a cable connection to say Thinkbroadband's BQM firebrick servers.
There are many other things that can cause browsers to appear to lag like slow DNS servers (try Google's on 220.127.116.11), Browser Plugins, Wireless Interference, Connection impairments, Busy servers, Firewalls, Hardware issues. etc. etc.
It would be worth testing with another browser and temporarily turning any software firewalls off.