(Note that this issue does not happen on Windows Server 2012.)
For Windows streamer version 18.104.22.168 or earlier:
When you type a key or click a button during a remote session, the screen doesn't update until tens of seconds or even several minutes later.
For Windows streamer version 22.214.171.124 or later:
During a remote session, screen updates are delayed by a few seconds and cursor keeps flashing. CPU utilization is also unusually high at 25-50%, even on a fast, multi-core CPU.
Version 126.96.36.199 introduced an optimization that reduces the delay on servers with low video memory from potentially minutes down to a few seconds, so such a system can at least be operable. It is still necessary to apply one of the two workarounds below so your server can operate the most efficiently.
If this is happening, it is an indication of Splashtop not having enough video memory to work with. For Splashtop to work efficiently, the computer should have at least 256MB of video memory. This is easily met by most PCs and off-the-shelf graphics cards nowadays (where 1GB+ is not uncommon). But it may not be met by many servers out there where 8MB or 16MB of video memory is still the norm.
The reason why Splashtop needs more video memory than traditional remote desktop tools is we use a video-based approach to encode and transmit the screen. That technology is key to achieving our performance goal of enabling users to feel as if they're still sitting in front of their computers (given sufficient hardware and network capabilities, of course).
However, this approach does mean we tax the graphics hardware more heavily.
You can run Windows's built-in DxDiag.exe to find out how much video memory the computer has. This support article shows where to look in DxDiag for the relevant info.
Network bandwidth is not likely the reason when the delay is so drastic. Insufficient network bandwidth may result in delays of up to several seconds, but usually no more. If you want to confirm whether network bandwidth is an issue, you can temporarily reduce the computer's resolution to 1024x768 or turn on smooth mode (in the Splashtop Business app), to see whether speed improves. These tests will not make a difference if the slowness is due to insufficient video memory.
Generally, Splashtop should be fairly responsive with 1.5 - 2Mbps of uplink from the computer being remotely accessed.
If the computer indeed does not have enough video memory, there are two proven workarounds available:
1. Disable hardware acceleration of the display adapter on the computer
This support article shows how you can do that.
This workaround has worked well for many users. For others, disabling hardware acceleration is not viable due to logistics or due to other workloads on the computer.
2. Install a mirror driver (reboot required)
With a mirror driver is installed, the Splashtop Streamer will use a different way to process the screen information.
Splashtop Streamer v188.8.131.52 and newer:
Open the Streamer program from the Start Menu -> All Applications -> Splashtop Remote -> Splashtop Streamer
Then click on the "Advanced" tab and scroll down to click on the "Install Mirror Driver" button. A UAC window confirming the install will popup. Click Install to continue. The Button will change to "Uninstall Mirror Driver" when complete.
Splashtop Streamer v184.108.40.206 to v220.127.116.11, manual install. (Tutorial Video available at: https://www.youtube.com/watch?v=rSn8DmYxSiA)
- Download and install the mirror driver from below (driver.zip).
- Unzip driver.zip
- Open a cmd window with "Run as administrator"
- Run the install.bat in the appropriate folder (xp/xp64 folder if you have XP or Server 2003; vista/vista64 folder if you have Vista, Windows 7, or Server 2008)
This workaround has been proven on a variety of HP and Dell servers with 8 or 16MB of video memory.
Note 1: If you had hardware acceleration turned off as a workaround for the slow performance, feel free to turn it back on after installing the mirror driver.
Note 2: If you do experience such drastically slow response times, but there is sufficient video memory, we would appreciate if you can let us know. There may be other causes that we aren't aware of. Please file a support ticket including the DxDiag output.
Note 3: There are two limitations when using Mirror driver. Please click into the link for more details.
Update (6/29/2015) - Switching between multiple monitors is now supported by default in Splashtop Streamer version 18.104.22.168 and later.
Update (3/25/2016) - Described the partial optimization added in version 22.214.171.124 of Windows streamer. Note that one of the two workarounds above is still necessary for systems with low video memory.