How fast is a class graded on your computer? How we test it
Teachers grade on a computer at school or on their own computer at home. We test grading speed in two states: an ordinary day on an ordinary computer, and a bad day on an older budget laptop. Here are all the numbers, how we measured them, and what they do not say.
The bottom line
On an ordinary day, on an ordinary 4-core computer at school or at home: 160 pages(measured) were graded in 4.1 minutes(measured), from the first page in the scanner to the last grade, with no measurable slowdown against an idle computer. For a class of 25 with a 2-page exam that is about 1½ minutes(calculation) of grading; for a class of 35, about 2 minutes(calculation). Every scan starts with a one-time preparation of a minute or two(measured), so a short scan takes a little longer than that.
On a bad day, on an older budget laptop with 2 cores, while the antivirus scans the whole computer the entire time: for a class of 25 with a 2-page exam, the last grade appears after about 18 minutes(calculation). For a class of 35, after about 26 minutes(calculation). The scanner itself feeds the pages in a few minutes, and nobody needs to stand by it: the grades keep appearing on their own.
When the computer is idle, 160 pages(measured) were graded in 4.4 to 4.8 minutes(measured) (two runs), from the first page in the scanner to the last grade. That is roughly the pace an office scanner feeds pages (20 to 60 pages a minute(estimate)).
On the ordinary day and on the bad day alike, all 160 pages(measured) got exactly the same grade as on the idle computer. Load slows grading down; it does not change a grade.
We measured the bad day on a 4-core test machine held to 1.2 cores, not on a real 2-core computer. That test is on its way, and we will update the numbers here.
- measured in a test
- estimate or calculation
- still being tested
Why two numbers, not one
Teachers grade on the computer at school, and on their own computer at home. Such a computer never does just one thing: a browser is open, Windows is downloading updates, the antivirus is checking files. And sometimes the computer is old.
So we do not test on an empty, fast machine. We build a computer of a set size, give it other work to do, and grade a whole class on it.
There are two ways to get this wrong. Publish only the bad day, and we scare people for no reason, because most days are not like that. Publish only the ordinary day, and we hide what happens on a bad one. So we publish both, side by side, and we tune the software against the ordinary day without letting the bad day break.
Two days, two computers
The computer: an ordinary computer with 4 cores and 6 GB of memory, at school or at home.
The setup: all four cores are available, and the disk is as fast as a cheap SSD. A browser is open holding 1 GB of memory, and there is a little disk work in the background. The antivirus runs its normal protection with no full scan, because Windows schedules full scans for when the computer is not in use.
The result: 160 pages(measured) were graded in 4.1 minutes(measured), against 4.8 minutes(measured) on the idle computer in the same test: no measurable slowdown(measured). The loaded scan ran second, on a machine that was already warm, so we do not claim it is faster. Each page spends 3.4 to 4.1 seconds(measured) being read: the QR code 1.6 to 1.9 seconds(measured), the marked bubbles 1.3 to 1.6 seconds(measured).
The grades: all 160 pages(measured) got exactly the same grade as on the idle computer.
The start: before the first page is graded, the app loads the exam's layout once: 61 seconds(measured) on the idle computer, 98 to 105 seconds(measured) on the ordinary day. We are looking at how to shorten it.
What it means for a teacher: on an ordinary day the app keeps pace with the scanner. For a class of 25 with a 2-page exam, the grading itself takes about 1½ minutes(calculation), after the one-time preparation of a minute or two. It is the number we aim our improvements at.
Side by side
| Ordinary day | Bad day | |
|---|---|---|
| The computer | ordinary: 4 cores, 6 GB of memory | older budget laptop: 2 cores, 4 GB of memory |
| Processor | all four cores | held to 1.2 cores |
| Disk speed | 1000(estimate) operations a second, like a cheap SSD | 300 operations a second, like an old hard disk |
| Open browser | holds 1 GB of memory | the same |
| Background disk work | 20 operations a second | 100 operations a second |
| Antivirus | normal protection only | full scan for the whole test |
| 160 pages, to the last grade | 4.1 minutes(measured) | 59 minutes(measured) |
| Same grades as the idle computer | all 160 pages(measured) | all 160 pages(measured) |
Why these two computers
We have no data on which computers Israeli schools or teachers' homes actually use, and we do not claim any. We chose the two computers from what can be checked:
- An ordinary computer, 4 cores. In Steam's hardware survey, the share of computers with 4 cores or fewer fell from 62% in November 2020 to 17% in November 2025 (Guru3D). It is a survey of gamers, whose computers are stronger than average, so it does not describe teachers. It does show how fast computers with more than 4 cores became common.
- An older budget laptop, 2 cores. Budget laptop chips from 2019–2020 have 2 cores, according to Intel's spec pages: the Celeron N4020 and the Core i3-1115G4. A newer budget chip such as the N100 has 4.
How many pages are graded in a minute
How long will your class take
We do not know how long teachers' exams are on average, so you can choose the pages per exam here. Scan time depends on the number of pages, not the number of questions. The exam we tested has 2 pages and 40 questions.
How long for your class?
50 pages to scan
- The scanner feeds every page
- about 1 to 3 minutes(estimate)
- The last grade appears on an ordinary day
- about 1½ minutes(calculation)
- The last grade appears on a bad day
- about 18 minutes(calculation)
The scanner finishes long before grading does. The other pages wait in a queue, and grades keep appearing after the last page has left the scanner.
Every scan starts with a one-time preparation of a minute or two before the first page is graded, so a short scan takes a little longer than the calculation shows.
These are calculations: the measured time for 160 pages, scaled to your number of pages. Scanner speed is an estimate.
How the test is run
- We set up a virtual machine with Hebrew Windows 11, sized like the computer under test: 4 cores and 6 GB of memory for the ordinary day, 2 cores and 4 GB for the bad day.
- We install the app and use it as a teacher does: first-time setup, a student list, and a Mishnah exam in 80 copies of 2 pages, 160 pages in all. Each copy is marked differently, so no two copies get the same grade.
- A simulated scanner feeds the 160 pages to the app, exactly like a real network scanner.
- A first scan with the computer idle. This is the point of comparison.
- We put the app back to where it was before the scan and start the load: the computer running the virtual machine limits its processor and disk, and inside Windows standard Microsoft tools run, not tools we wrote ourselves.
- We scan the same 160 pages again, under load. The load stays until the last page is graded.
- We compare: every grade must be identical to the first scan, and the app must keep responding the whole time. If a single grade differs, the test fails.
What we measure
- How long it takes from the first page in the scanner to the last grade.
- How long each page spends being read (seconds per page).
- How many times slower grading is under load.
- That every grade matches the scan on the idle computer.
- That the load really was applied as set: the processor and disk limits are read back, and the tools ran throughout the scan.
Glossary
- CoreCPU core
One working unit of the processor. A computer with 2 cores can truly do two things at the same time. Budget laptops from 2019–2020 usually have 2; newer budget chips have 4.
- vCPUvirtual CPU
A core that a virtual machine gets from the computer running it. We set 4 for the ordinary day and 2 for the bad day.
- Virtual machine
A whole computer, with its own Windows, running as a program inside another computer. It lets us set exactly how strong it is and repeat the same test again and again.
- CPU cap
The host gives the virtual machine only part of its processing power. On the bad day: 1.2 cores only, like a computer busy with other things.
- IOPSinput/output operations per second
How many times a second the disk can read or write a piece of data. An old hard disk does few, an SSD far more. We capped it at 300 for the bad day and 1000 for the ordinary day.
- Defender full scan
The antivirus built into Windows goes through every file on the computer. It takes a long time and slows the computer down. Windows usually does it when the computer is not in use. On the bad day we ran it for the whole test.
- Real-time protection
The antivirus checks each file the moment it is opened. It is always on, on every computer, and in both states.
- TestlimitSysinternals Testlimit
A Microsoft tool that takes some memory and holds on to it. In the test it holds 1 GB, like a browser with many tabs open.
- DiskSpdMicrosoft DiskSpd
A Microsoft tool that reads and writes to the disk at a fixed pace, like a file copy or an update running in the background.
- Seconds per page
How long one page spends being read: its QR code, the corner marks and the marked bubbles.
- Pages per minute
How many pages go from the scanner to a grade each minute. Here it is worked out from the time for all 160 pages. Because the app reads several pages at once, this is not simply 60 divided by the seconds per page.
- Worker
The part of the app that reads one page. In the test up to four ran at once, so four pages were read at the same time.
- Queue wait
When the scanner is faster than grading, scanned pages wait in line until their turn. They are not lost; their grades simply appear later.
- OMRoptical mark recognition
Automatic reading of the bubbles a student marked on the page. It is what the app does to every scanned page.
- Build
One particular version of the app. Every result here belongs to the build that was tested, and we name it.