Process Lasso Features
Set permanent CPU affinities, priorities and other process settings, change power plans when a specific application is running, or constrain a process once it exceeds a certain level of CPU use. Create your own rules, or let Process Lasso’s automated algorithms do it for you.
Wildcards and regular expressions are accepted in most rules. See process matching.
Overview
Each rule is applied every time a matching process runs, so you set it once. Jump to a feature below, or open its page in the Process Lasso documentation.
Right-click any process to change a setting for the current instance only, or use the always submenu to create a persistent rule that applies every time the process runs. Each kind of rule can also be managed in one place, at the menu paths shown below.
To target every process launched by an application, use a childof: match, such as childof:steam.exe.
Rules you create are shown in shorthand in the process list’s Rules column. Some common symbols:
See the full Rules column legend.
CPU and Scheduling
Keep applications running at specific priority classes every time they launch: Real-Time, High, Above Normal, Normal, Below Normal or Idle. I/O and memory priorities can be set the same way, and GPU priorities at Options / GPU / GPU Priorities.
Raising a priority class generally won’t make an app go faster. It is usually better to lower the priority of problematic background processes, which is what ProBalance does automatically.
Priorities in the docs
A CPU affinity controls which CPU cores a process is allowed to use; its threads are only scheduled to that set of cores. Use it to dedicate cores to specific apps, games or services, or to cap the maximum CPU a process can consume.
The optional Delay field applies the affinity a number of seconds after the process starts. This helps games and apps that are sensitive to affinity changes while they start, or gives a process the full CPU while it loads before restricting it.
On systems with more than 64 logical cores, Windows restricts affinities to one processor group. Process Lasso reapplies persistent affinities so new threads follow them, but CPU Sets have no multi-group restrictions. To limit CPU use only when a process misbehaves, use the CPU Limiter instead. The dialog is shown at the top of this page.
CPU Affinities in the docsThe CPU Affinity context menu has an item that disables SMT (Hyper-Threading) for a process, by enforcing an affinity with only one logical core from each physical core. On most CPU models this produces an alternating affinity pattern.
To find your strongest cores first, try the free ThreadRacer benchmark, or work out affinity masks with the CPU Affinity Calculator.
CPU Sets, a native Windows feature, are a softer form of CPU affinities: A suggestion of preferred cores rather than a hard contract. The OS tries to abide by a CPU Set but can schedule outside it when the thread load exceeds the cores in the set, or for power management. For performance tuning, CPU Sets are usually preferred; for hard limits on CPU use, use CPU affinities.
Apps and games that are sensitive to affinity changes are less likely to have problems with CPU Sets. On hybrid CPUs such as Intel 12th Gen (Alder Lake), CPU Sets can keep select applications on the performance (P) or efficient (E) cores, or a mix of each. On systems with more than 64 logical cores, add a set for each processor group the process should span.
CPU Sets in the docs
Efficiency Mode, introduced in Windows 11, tells the OS a process is not time-critical, so it may be deprioritized, run at a lower clock speed or scheduled to E-cores. Windows has no way to make the setting stick; Process Lasso persists it ON or OFF per process.
The Status column shows Efficiency for processes in Efficiency Mode, and the Rules column shows E for always ON and e for always OFF. ProBalance can also put the processes it restrains into Efficiency Mode; that option is off by default because it is more heavy-handed than ProBalance’s normal priority adjustment.
Efficiency Mode in the docs
Windows temporarily boosts the priority of threads when they wake to resume work. It is on by default for new processes and should normally stay on, but Process Lasso can turn it off per process with the Thread Boost context menu. A hyphen after the priority class name shows it is off.
Thread Boost in the docsRaises the priority class of the process in the foreground. Windows already boosts the foreground, so further boosting is usually not effective, and ProBalance works in the opposite direction for a reason. Still, it can be useful in some environments, and on hybrid CPUs it is an easy way to signal that the foreground process should prefer P-cores.
Foreground Boosting in the docsTemporarily raises matching processes to Above Normal or High priority for 1 to 3600 seconds after they start, optionally with Efficiency Mode off while boosting, then restores the prior priority class. Right-click a process and choose More / Startup Boost to add a rule.
Startup Boost in the docsProcess Control
Processes on this list are terminated as soon as they are found running. Process Lasso can’t prevent them from trying to start; it terminates them immediately when it finds them.
Disallowed Processes in the docs
“If, then” rules that act on a process when it exceeds an amount of CPU or memory for a time you set. Actions include changing the CPU affinity or priority class, setting the I/O priority, restarting or terminating the process, trimming its virtual memory, running an external program, and logging the occurrence.
On high core count systems, CPU thresholds can be divided by the logical core count for more precision.
Watchdog in the docs
Automatically restarts select processes when they terminate, so they come back after a crash or when they become unresponsive. Right-click a process and choose Keep process running. Processes it launches run unelevated unless you enable elevated launches.
Keep Running in the docsLimits how many instances of a process may run at the same time in each user session. New instances are terminated when the limit is already reached.
Instance Count Limits in the docsWhen a matching process stays above a CPU threshold for a set period, the CPU Limiter removes cores from its affinity for a set time, capping how much CPU it can use, then restores the original affinity. If your goal is a responsive PC under load rather than lower CPU numbers, ProBalance does that without reducing CPU use.
About the CPU LimiterSelect several processes at once and act on them together, for example to terminate them all. Not every function is available with multiple processes selected, but most common ones are.
Multi-select in the docsPower and Sleep
Switch the system to a chosen power plan while specified processes are running, and back to the previous plan when they exit. Right-click a process and use the Power Profile submenu, or manage the rules from the Options menu.
Start With Power Profile (Options / Power / Start Process Lasso with Power Profile) sets the power plan the system uses when Process Lasso starts and whenever no power rules are active. It prevents ending up in an unwanted plan after conflicting rules or outside changes.
Power profiles in the docs
Choose a power plan for when the PC is idle. Run a high performance power plan while you’re active, without giving up all energy savings: IdleSaver switches to a more conservative plan while you’re away.
More about IdleSaver
Keep the PC and display from sleeping or hibernating for a specified amount of time, or while select processes are running. Right-click a process and use the Prevent Sleep submenu to add one.
Keep Awake in the docsConfig profiles are named sets of all your rules and settings, such as Gaming and Productivity. The switcher changes profiles when specified processes run and restores the prior profile when they exit. Use it sparingly, and give each profile rules that undo the others’ changes.
Config Profile Switcher in the docsSystem Tools
Adjust the system timer resolution in up to 0.5 ms increments, and keep the change across reboots, which other tools don’t do. We can’t speak to the general efficacy of this tweak, though there are cases where it is desirable. Starting with Windows 10 version 2004, it has no effect on processes that don’t request a timer resolution themselves unless Apply globally is checked.
System Timer Resolution in the docsSetting a higher resolution can improve the accuracy of time-out intervals in wait functions. However, it can also reduce overall system performance, because the thread scheduler switches tasks more often. High resolutions can also prevent the CPU power management system from entering power-saving modes.
Microsoft Learn: timeBeginPeriod function
Process Lasso contains many other features and functions. Explore them in the Process Lasso documentation.
All of these rules are part of Process Lasso. Running Windows Server? See Process Lasso Server Edition.
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