It’s perfectly normal to see two or more iexplore.exe processes in the Task Manager when an Internet Explorer 8 window is open. This is due to a change implemented in Internet Explorer 8 where the frame and tabs are split, each having their own processes. Each tab has its own* process so that the rest of the tabs and the browser frame/window are not affected when a single tab process crashes.
Note: If you have 60 tabs open you won’t see 60 iexplore.exe processes. There may 20 iexplore.exe processes, with each process hosting a number of tabs. As per the IE Team Blog, this a balancing act between performance and reliablility. Quoting from Internet Explorer Team Blog:
The more capable your system is, the more processes we create, up to a point. It’s based on a curve. If you use 60 tabs at a time, we don’t want to create 60 tab processes, as the perf impact would be too severe. It’s a balancing act between performance and relability. For example, if you had 60 tabs open and we created 20 processes, we would co-locate 3 tabs in each process (60 tabs / 20 processes). If a single tab process failed, we would only have to recover 2 other tabs. The benefit of "perfect" isolation would not be worth the cost of 40 extra processes in most cases. It’s a case of diminishing returns.
Apart from this, there are other architectural changes made in Internet Explorer 8, which is collectively known as Loosely-Coupled IE (LCIE). For detailed information on these changes, see the following posts at the IE Team Blog.
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The IE 8 Process Model is Configurable
The IE team has documented a single registry value that controls the new process model. If you create a DWORD value called TabProcGrowth in:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
you can control how many browser processes are used by IE 8:
The three most useful values for this setting are:
1.TabProcGrowth = – this is the default setting allowing IE 8 to control how many processes are used based on the amount of physical memory installed
2.TabProcGrowth = 0 – a value of zero means use the same process for all tabs, frames and pop-up windows in each browser session. This makes IE 8 behave just like IE 7 on Windows XP. There’s no frame merging and clicking on the IE icon creates a new instance of iexplore.exe in a separate browser session. Protected mode on Vista is not available with this setting because the IE frame and tabs can only operate at different integrity levels if they are in separate processes. This setting may be useful if you are debugging an IE add-on or if you have automated tests that rely on the IE 7 process model.
3.TabProcGrowth = 1 – this means use one process for all the tabs and pop-ups in a browser session and one process for the IE 8 frame window. Frame merging occurs with this setting and protected mode is supported on Vista. You may want to use TabProcGrowth = 1 where you want to keep tabs and pop-ups in one process but still allow the use of protected mode.
Specifying a number greater than 1 sets an upper limited on the maximum number of tab processes to use per frame window process.
Thanks Caz!
A friend was describing the same issue to me and I found your suggestion and turns out he had the D addon. The key difference with the presence of this addon is the memory usage viewable via task manager. The new propagations of ie all had much much greater memory usage than the typical page.
Ross, same problems with IE 8 as you. Although I do not use IE 8 but others in my family do, I had to figure out a fix. Using “Hijack This” in admin mode, I deleted an IE 8 add-on named “D”. Turns out this add-on had an unverified signature and little to no details. This cleared up our issue.