You currently get DNS from the ISP, via DHCP.
You can enable DNS, and then put in the DNS servers statically, and see if that helps, but if it is a problem contacting the DNS server, then static or dynamic, the problem still exists....
Sounds more like an IP stack issue for Win98. You could try Windows update, and install any pathes/service packs... and update the browser to the latest service pack.
If it was DSL, the MTU setting could be adjusted a little lower than the default of 1500.
Also, I dont know if this will help this specific issue, but Win98 needs it TCP receive window (RWIN) bumped up.
You can download this file: [url]http://www.dslreports.com/front/tweak/rwin98-l.reg[/url] for WINDOWS 95/98 ONLY!!!
Save it to disk, then execute it. Reboot. Makes broadband under Windows 95/98 MUCH smoother.