Content expiration is disabled both for that file and the directory it's in. So unless a user has changed the defaults and their browser is being very aggressive about not caching, the logo itself should very rarely get sent. And it's only 2745 bytes. From a server that's pretty busy but always shows very low utilization. 4-5% right now.
I just double-checked, and am very sure that a subscriber browsing through messages never touches that server except to get the logo if it's not cached.
To anyone curious about how the ads/no-ads thing works, it's one of the beauties of ASP. If the programs determine that you're a subscriber, they never include the HTML that'll pull up an ad. That's why response times (when the ISP isn't flaking out) are MUCH better for subscribers than non-subscribers. The logic doesn't go "Grab an ad but don't display it if they're a subscriber." It goes "If they're not a subscriber, grab ads and display them."
Subscribers are only interacting with our servers, which are very fast. Non-subscribers can be interacting with as many as 4 ad servers that're far slower than our servers are. Our own ad server is extremely fast, but when delivering an ad that we're not hosting in-house (Schwab and Refco are the in-house ones), there can be a big delay while waiting for an ad to arrive from one of our agencies.
