This is Shahinur continuing our discussion on IE8 changes related to its Loosely Coupled IE design.
In previous versions of the browser, when you start a new instance of Internet Explorer (by clicking on the blue e in taskbar, for example) you will notice that a new iexplore.exe process starts. If you are a user who does this often, you could run up your process count pretty easily, especially now that you have separate frame process and a tab process in IE8.
In order to solve this problem and save system resources, IE8 has a feature called “Merged Frame Process” or MFP. When a frame process starts, MFP makes an intelligent decision as to whether it can and should merge into an already running frame process. The decision involves maintaining the separation of session context (eg, session cookies) between sessions among other things. In addition, various conditions (such as running with “no add-ons”, “ie7emulate”, “admin”, “private browsing mode”, being the same user) must match between two frame processes in order for them to merge.
Once the merge decision has been made, the new frame process will communicate to the existing one and then exit. In this way, we minimize the number of IE frame processes IE8 uses for the logged on user. This is a large performance improvement for users that “click the blue e” instead of creating new tabs.
Be careful not to confuse the frame process with the tab process. Let’s say you keep launching IE from your taskbar while all other conditions remain the same, you will end up with only one Frame process but possibly several Tab Processes. The number of tab processes will be based on the Tab Process Growth algorithm I explained in my earlier blog.
If you do not want frames to merge, you do have option to control it both with a regkey and with iexplore.exe command line switches.
Command Line switches:
“-FrameMerging” – regardless of the user’s default, this iexplore.exe frame process will merge with another compatible frame process.
“-NoFrameMerging” – regardless of the user’s default, this iexplore.exe frame process will not merge with any other frame process.
Registry key details:
0 – disable frame merging
1 – enable frame merging (default)
The IE team