It's probably due to both SQL and SolarWinds. By default, when we load that page, we are trying to load the most recent 250 trap messages. If the DB is slow to respond, then we could timeout when trying to load the page. The DB may be slow because you have a lot of syslog(mean the query takes a long time) or you have a lot of syslog messages coming into the database, preventing our read from occuring in a timely manner.
One thing to check is that you're trying to pull a more reasonable number of traps to begin with, in the WebUserSettings table in the database, look for the Web-TrapMaxMsgPerPage row. Make the value in the SettingValue column is set to something reasonable like 250 for the user you're using. If that number is really high, you may want to check out the default value for a user on the Web Settings page available from the Admin section of the website.