Follow the recommendations here to improve overall performance of Second Life and address many common problems.
Make sure your computer meets the Minimum system requirements. It's best to exceed them to prevent bottlenecks, since they are the bare minimum required to run Second Life. A slower processor, older video card, or low memory can contribute to slow framerates.
Make sure you have working drivers for your video card. Search the SL Forum for posts on your video card. The latest driver is not always the best.
Check to see if your hard drive light is showing a lot of activity. If it is, your system may be running low on memory and using hard drive swap space instead, which is significantly slower.
Based on statistics collected by Linden Lab:
If you are using Windows 8, make sure you have upgraded to Windows 8.1. Our statistics show that Second Life crashes half as often on Windows 8.1 compared to Windows 8.0.
If you are using Mac OSX, upgrade to 10.9.3. Our statistics show that 10.9.3 crashes one third less than 10.7.5.
Use a 64-bit version of Windows if you can. Even though we don't offer a fully 64-bit viewer for Second Life as of July 2014, our statistics show that Second Life running on 64-bit operating systems crashes half as often as on 32-bit systems.
Important: Second Life allows but does not support wireless connections. Always use a hardwired connection if possible.
Optimize your display preferences
Optimize your preferences to help Second Life run more efficiently. Try the following:
Choose Me > Preferences
Click on the Graphics tab.
Move the Quality and speed slider to Low.
Click the Advanced button
Move the settings on the Mesh detail sliders to "Mid" or "Low."
Autoplaying music and media can be very demanding on some PC equipment. Use manual play instead:
Choose Me > Preferences > Sound & Media
Deselect Allow Media to auto-play.
Review the rest of your preference settings disable any unused features:
Choose Me > Preferences or press Ctrl-P).
Try disabling settings such as Play typing animation, Name tags, and Arrow keys always move me.
Even minor items can add up to significant improvements in performance.
Make sure your Viewer is not displaying unnecessary information that may reduce performance:
Choose World > Show> Advanced Menu.
Choose Advanced > Highlighting and Visibility.
Select Hide Particles.
Choose World > Show
Disable Property Lines and Land Owners.
This will improve performance by eliminating gratuitous visual noise.
Manage your antivirus software
To prevent false cache virus alerts and improve texture cache performance, turn off virus scanning for the following directories and add them to the list of ignored (trusted) directories for Norton AntiVirus:
The Second Life skins directory, C:\Program Files\SecondLife\skins.
The Second Life cache directory. To determine this directory:
Choose Advanced > Performance Tools > Statistics Bar to open the STATISTICS window.
The ping values are the time (in milliseconds) it takes to reach the server from your computer. If this number is high, it could indicate a problem with your network or internet connection. If Packet Loss is a nonzero number, your network or ISP may be having issues. See Using the statistics bar for more information.
Check to see if there is anything blocking your computer's ventilation ports, and make sure all the fans are working properly. Laptops in particular can get quite hot when placed on a flat surface, so you may want to try propping yours on a stand to increase airflow, or consider buying a cooling device like a "chill mat".
Finally, if you've overclocked or made other modifications to your computer, disable them until you can attain stability. You can use tools like Prime95 to stress-test your computer independently of Second Life.
Using the statistics bar
The statistics bar presents a detailed list of information about the performance of your computer and Second Life. While the sheer amount of information can be confusing, knowing what to look for can tell you a lot about what's going on in Second Life.
To view the Statistics Bar, choose Advanced > Performance Tools > Statistics Bar.