Intel Hybrid CPUs: Scheduling on P-Cores and E-Cores

Since the 12th generation (Alder Lake), most Intel processors combine two kinds of cores: performance cores (P-cores) for demanding work, and smaller efficient cores (E-cores) that add multithreaded throughput at lower power. Many laptop chips add a third kind, low-power E-cores (LP E-cores). Windows decides which kind of core each thread runs on, and most of the time it chooses well. This page covers which CPUs are hybrid, how Windows decides, when it gets it wrong, and how to fix that with Process Lasso.

Which CPUs This Applies To

Desktop

Generation	Hybrid models (P-cores + E-cores)	Not hybrid (P-cores only)
12th Gen Core (Alder Lake)	Core i9-12900K, 12900KF, 12900KS, 12900, 12900F (8 + 8); Core i7-12700K, 12700KF, 12700, 12700F (8 + 4); Core i5-12600K, 12600KF (6 + 4)	Core i5-12600, 12500, 12400, 12400F; Core i3-12100, 12100F
13th Gen Core (Raptor Lake)	Core i9-13900K, 13900KF, 13900KS, 13900, 13900F (8 + 16); Core i7-13700K, 13700KF, 13700, 13700F (8 + 8); Core i5-13600K, 13600KF, 13600, 13500 (6 + 8); Core i5-13400, 13400F (6 + 4)	Core i3-13100, 13100F
14th Gen Core (Raptor Lake Refresh)	Core i9-14900K, 14900KF, 14900KS, 14900, 14900F (8 + 16); Core i7-14700K, 14700KF, 14700, 14700F (8 + 12); Core i5-14600K, 14600KF, 14600, 14500 (6 + 8); Core i5-14400, 14400F (6 + 4)	Core i3-14100, 14100F
Core Ultra 200S (Arrow Lake)	Core Ultra 9 285K, 285 (8 + 16); Core Ultra 7 270K Plus (8 + 16); Core Ultra 7 265K, 265KF, 265, 265F (8 + 12); Core Ultra 5 250K Plus (6 + 12); Core Ultra 5 245K, 245KF, 245, 235 (6 + 8); Core Ultra 5 225, 225F (6 + 4)	None

On the 12th to 14th Gen models, each P-core has Hyper-Threading and shows up as two logical processors, while each E-core shows up as one. Core Ultra 200S processors have no Hyper-Threading, so every core is one logical processor.

Laptops

Family	Examples (P-cores + E-cores + LP E-cores)
12th to 14th Gen Core H, HX, P and U	Core i9-14900HX and i9-13980HX (8 + 16); Core i7-12700H (6 + 8); Core i5-1235U (2 + 8)
Core Ultra Series 1 (Meteor Lake)	Core Ultra 7 155H (6 + 8 + 2); Core Ultra 5 125H (4 + 8 + 2); Core Ultra 7 155U (2 + 8 + 2)
Core Ultra 200V (Lunar Lake)	Core Ultra 7 258V (4 + 0 + 4)
Core Ultra 200H and 200HX (Arrow Lake)	Core Ultra 9 285HX (8 + 16); Core Ultra 9 285H (6 + 8 + 2)
Core Ultra Series 3 (Panther Lake)	Core Ultra X9 388H and X7 358H (4 + 8 + 4)

Intel’s N-series processors, such as the N100, N150, N200 and Core i3-N305, have only E-cores, so there is no core type to choose. For AMD processors with two core chiplets and 3D V-Cache, see AMD Ryzen X3D CPUs: Keeping Games on the 3D V-Cache CCD.

How Windows Decides Where Threads Run

Intel Thread Director: The processor reports what each thread is doing, and Windows 11 uses that to pick a core type. Windows 10 schedules hybrid CPUs without most of this guidance, so it makes more poor choices. Windows 10 has also been out of support since October 2025.
Which window you’re using: Windows 11 treats the program in front of you as the most important. Programs in the background or minimized rank lower, especially on battery, and their threads are the ones Windows moves to E-cores.
Efficiency Mode: Programs can put themselves, or some of their threads, in Efficiency Mode (for example, browsers do this for background tabs), and Task Manager can do it too. Windows runs those threads on E-cores at low clock speeds.
Power settings: The power plan’s scheduling policies for short- and long-running threads, and the Windows power mode (Best performance, Balanced or Best power efficiency), change how readily Windows uses the E-cores.

Where It Goes Wrong

Work you aren’t watching: A render, encode, compile or export left running in the background or minimized can move to the E-cores and slow down a lot.
Games and real-time software in the background: Switching away from a game, or playing on a second screen while you use another window, can move game threads to E-cores. The same goes for audio software, voice chat and streaming software.
Important threads on E-cores in the foreground: Occasionally a game’s or application’s busiest threads land on E-cores even while you use it, causing stutter or slowdowns.
LP E-cores: On Meteor Lake, Lunar Lake and Panther Lake laptops, the LP E-cores are the slowest cores in the chip, meant for light background work.
Older software: A few older programs misbehave on hybrid processors. Keeping them on the P-cores usually fixes it.

Fixing It With Process Lasso

These options go from gentlest to strictest. Start with the first, and move on only if it isn’t enough. All of them are rules that Process Lasso applies every time the program starts.

1. Efficiency Mode Off

Right-click the program and choose Efficiency Mode, Always, Off. Process Lasso then keeps Windows from putting the program, or any of its threads, in Efficiency Mode, which is the main route to the E-cores. It doesn’t forbid the E-cores, so Windows can still use them when the P-cores are busy. See Efficiency Mode in the documentation.

Process Lasso process context menu with Efficiency Mode, Always, Off selected — An Efficiency Mode Off rule, set from the process context menu.

2. CPU Sets on the P-Cores

Right-click the program, choose CPU Sets, then Always, click P-Cores and then OK. CPU Sets are a strong preference: Windows keeps the program on the P-cores but may use other cores when it has to.

Process Lasso Assign CPU Sets dialog on an Intel CPU with 8 P-cores and 16 E-cores, with the P-Cores button selecting CPUs 0 to 15 — CPU Sets on a processor with 8 P-cores and 16 E-cores: *P-Cores* selects CPUs 0 to 15, and the E-cores are marked with an E.

3. CPU Affinity (Strict)

Right-click the program, choose CPU Affinity, Always, Select CPU Affinity, and click P-Cores. A CPU affinity is a strict limit: The program never runs on the E-cores, even when the P-cores are busy. It also works the other way round: Click E-Cores to send a long background job to the E-cores, so it keeps going without taking P-cores from what you’re doing.

Process Lasso Select CPU Affinity dialog on an Intel CPU with 8 P-cores and 16 E-cores, with the E-Cores button selecting CPUs 16E to 31E — A strict affinity that sends a background job to the E-cores.

Don’t count core numbers yourself. The order of P-cores and E-cores differs between generations, and the P-Cores and E-Cores buttons always select the right ones.

4. Performance Mode

Right-click the program and choose Induce Performance Mode. While it runs, Process Lasso switches to the Bitsum Highest Performance power plan, which keeps every core unparked and, when the PC is plugged in, tells Windows to prefer P-cores for both short- and long-running threads. See Performance Mode.

Other Tools

ParkControl: Changes the short- and long-running thread scheduling policies of any power plan, for example to prefer performant processors.
CoreDirector: A free utility that does one thing: It keeps the programs you choose off the E-cores, using Efficiency Mode Off, CPU Sets or CPU affinity.
Intel Application Optimization (APO): On supported processors, Intel’s own tool tunes thread placement for a list of supported games.

What to Avoid

Turning off the E-cores in the BIOS: That gives up their throughput for everything to fix a problem that usually affects one or two programs. Rules for those programs are more targeted.
Putting everything on the P-cores: The E-cores add a lot of throughput to renders, encodes and compiles. Leave all-core work unrestricted unless you are deliberately moving it out of the way.
Restricting system processes: Windows components, driver services and security software expect to run anywhere.

ProBalance keeps working alongside all of these rules; there’s nothing to change there.

Checking the Result

Process Lasso’s CPU core graphs mark the E-cores with a leaf icon, so you can see which kind of core a busy program is using. Watch the program in the situation that caused trouble, such as minimized or in the background, and remove the rule if it doesn’t help.