Memory management
LargeSystemCache
A server memory policy that usually hurts desktops
Last updated
Should you enable LargeSystemCache?
LargeSystemCache tells the memory manager to favour the system file cache over process working sets. It is a server-oriented policy, it is off by default on client Windows for a reason, and turning it on can make an interactive machine feel worse by trimming the working set of the application you are actually using.
Registry location and values
LargeSystemCache
- Location
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management- Value name
LargeSystemCache- Type
REG_DWORD- Default
- 0 on client Windows
| Value | What it does |
|---|---|
0 | Favour process working sets. The client default. |
1 | Favour the system file cache. The server-style policy. |
What Windows actually does with this
The memory manager balances physical memory between process working sets and the file cache. With LargeSystemCache set, the cache is allowed to grow at the expense of working sets, so file data stays resident longer while application pages are trimmed sooner.
What it affects
Memory pressure distribution. On a file server serving the same data repeatedly, favouring the cache is correct. On a desktop running one large application, trimming that application's working set to cache file data it will not re-read is the wrong trade.
Is it worth changing?
Do not enable it on a gaming desktop. The name suggests more caching and therefore more speed, which is why it appears in tweak lists, but the trade being made is against the working set of your foreground application. Windows client defaults to 0 deliberately. If you have plenty of RAM the setting is close to irrelevant; if you are memory-constrained it is actively harmful.
What can go wrong
Increased paging of application memory under pressure, which presents as stutter -- the symptom people usually set this value hoping to fix.
How to undo it
Set to 0 and restart.
Create a System Restore Point before editing the registry. Every setting on this page is reversible, but a restore point is the difference between undoing one change and reinstalling Windows.
Which Windows versions this applies to
All modern Windows versions.
LargeSystemCache: common questions
I have 32GB of RAM. Does it matter?
Much less. With ample headroom the memory manager is not forced into the trade-off this setting biases. That is a reason it does nothing for you, not a reason to enable it.
Sources
Does JINSHI Tweaks change this?
This page documents a setting that corresponds to the following toggle in JINSHI PC Tweaks: Large System Cache.
The reference above is written to be usable without the product. Everything here can be applied by hand for free. What the application adds is that the change is applied in one pass, the original value is stored first, and each toggle can be reversed individually. PC Tweaks does not create a System Restore Point for you, so make one before the first run. The JINSHI Tweaks homepage explains what the four apps include.
Related settings
Guides that cover this setting
Every change JINSHI PC Tweaks can make is listed on the complete tweak list, and the product itself is described on PC Tweaks for gaming.
If you would rather not do it by hand
JINSHI Tweaks: all four apps
£29.99one-time
Get all four appsEvery change can be reversed on its own. No subscription, nothing to renew.