Using Wi-Fi over a wired connection at home could bring your speeds down about 30 percent, suggests a new study out today by broadband research firm Epitiro.

Tracking the broadband connections of sample users in the U.S., U.K., Italy, and Spain, Epitiro found that on average people lost around 30 percent of their download speed using Wi-Fi over wired. Further, Wi-Fi users ran into a 10 to 20 percent increase in latencies, or delays, when downloading content.

Why such a disparity in performance Many Wi-Fi routers use the same default communications channel, which can create interference with neighboring networks. To solve that issue, Epitiro advises Wi-Fi users to try a different channel to see if performance improves, a process explained in Step 6 of this Microsoft document on improving your wireless network.

But Epitiro also points out that Wi-Fi performance can be degraded by physical items, such as walls and furniture, and bump into interference from other wireless devices using the same frequency, such as cordless phones, TV remotes, and even baby monitors. The Microsoft document also offers suggestions on resolving interference problems as well as other issues.

The good news is that actual Web page download times between Wi-Fi and wired connections were just about the same, according to Epitiro's findings, indicating that they're less affected by changes in line speed.

One handy Web site that can show you your broadband speeds is Speedtest.net. Running the site's performance tests will measure your download and upload speeds and tell you how they compare with those of other users.

To compile its data, Epitiro checked and compared the performance of 14,001 users across the four countries, with 56 percent hopping onto the Internet via Wi-Fi and 44 percent through wired Ethernet connections. The study was conducted from November 2010 to February 2011.