Section 2: Performance Tab

The Big Picture: From Single Rows to the Whole Machine

The Processes tab answers "who is using the PC?". The Performance tab answers "how is the PC doing overall?". It is like the dashboard of a car: speed, fuel and engine temperature, all as live graphs.

On the left (Windows 10) or in the side menu (Windows 11) you see small thumbnails: CPU, Memory, Disk, Ethernet or Wi-Fi, GPU. Click one to open a big graph. Every graph shows the last 60 seconds, with the newest moment on the right edge.

2.1 CPU Graph (Utilization, Speed, Processes, Threads, Handles)

What it is: The CPU page shows how busy the processor is, and facts about the processor itself.

Here is a real one. It belongs to an Intel Core i9-9900K PC with German-language Windows, so the labels are in German. The English meanings are in the table below the picture.

Figure 11.4 — The Performance tab, CPU page, on a PC with an Intel Core i9-9900K. The 16 small graphs are the 16 logical processors. Screenshot: PantheraLeo13595 (Microsoft Corporation software), public domain, via Wikimedia Commons.

(German numbers use a comma where English uses a dot: "3,21 GHz" means 3.21 GHz.)

Read the picture like an expert:

• 8 cores, 16 logical processors. Each core runs two threads at once. This is hyper-threading (SMT), exactly as in Chapter 2. That is why you see 16 small graphs, one per logical processor. Windows treats each as its own CPU.
• Speed 3.21 GHz, base speed 3.60 GHz. Base speed is the "official" clock. Speed is the current clock, which moves up and down all the time to save power (Chapter 4's P-states) or go faster in turbo. At 8% load, the CPU was relaxing a little under base speed.
• Virtualization: Disabled. The CPU can run virtual machines, but the setting is off in firmware. Hyper-V support: Yes means the CPU has the features Windows needs for it.

Useful right-click options on the graph:

• Change graph to → Overall utilization shows one big graph (the average).
• Change graph to → Logical processors shows one graph per logical processor (as in the figure).
• Show kernel times adds a darker area for time spent in the operating system itself (kernel mode), and the lighter area is your programs (user mode).
• Summary view (double-click the graph area) shrinks the window to a small floating graph.

Why this matters: If one logical processor is at 100% and 15 are asleep, a single thread is the limit (Chapter 10). If all 16 are busy, the whole CPU is the limit.

2.2 Memory Graph (In Use, Available, Committed, Cached, Paged/Non-Paged Pool)

What it is: The Memory page shows how your RAM (Chapter 3) is being used. The top graph is memory usage, and a second graph shows memory composition.

Memory composition bar (not to scale)

 ┌────────────────┬───────────────┬────────────┬──────────────┐
 │ In use         │ Modified      │ Standby    │ Free         │
 │ (programs)     │ (to be saved) │ (cache)    │ (empty)      │
 └────────────────┴───────────────┴────────────┴──────────────┘
   "Available" = Standby + Free (can be handed out quickly)
   "Cached"    = Modified + Standby

Beginner trap: "My RAM is 80% used, is that bad?" Not by itself. Windows likes to fill spare RAM with cache because empty RAM is wasted RAM. What matters is whether Available stays healthy and whether Committed is far from its limit. The real warning sign is when the PC becomes slow and the disk is busy: Windows is moving pages to and from the page file ("paging").

Pools in one line: If non-paged pool keeps growing without stopping, a driver may be leaking memory. This is a common reason for "my PC slows down the longer it runs".

2.3 Disk Graph (Active Time, Read/Write Speed, Response Time)

What it is: One Disk page per physical drive, named Disk 0 (C:) and so on, with the model and type (SSD or HDD) in the top corner.

Two graphs are shown: Disk transfer rate (read as a line, write as a dotted line) and Active time (the top graph).

Why the response time matters more than the percentage: A hard drive has a spinning platter and a moving arm (Figure 11.3). Every request to a different place needs the arm to move. If many programs ask at once, requests queue up and the response time climbs, and the PC feels frozen, even if the speed figure looks low. An SSD has no moving parts, so it handles many small requests far better.

Windows tip: If a hard-drive PC is slow at start-up and Disk shows 100% active with a response time over 100 ms, many programs are fighting for the disk. Cut the startup list (Section 4).

2.4 Network Graph (Throughput, Adapter Info)

What it is: One page per network adapter, named Wi-Fi or Ethernet. The graph shows throughput (the amount of data per second) sent and received, with the scale at the top-left that adjusts automatically.

Bits vs bytes (a common mix-up): Network speeds are quoted in bits, file sizes in bytes. One byte is 8 bits, so a connection moving 80 Mbps transfers about 10 MB/s. If Task Manager shows 80 Mbps and your download window shows 10 MB/s, both are right.

Important: This graph shows the traffic of the whole adapter. To find which program is sending, go to the Processes tab and sort by Network (Section 1).

2.5 GPU Graph (Engines, Dedicated/Shared Memory)

What it is: If your PC has a graphics chip, you get a GPU page for each one: GPU 0, GPU 1 and so on. Laptops often have two: a small one inside the CPU and a stronger one from NVIDIA or AMD.

A GPU is built with several engines, which are separate blocks that do separate jobs at the same time. The page shows four graphs by default. The names depend on the driver, but you will often see:

You can click the small arrow on a graph title to change the engine it shows (for example "Compute" for tools that use the GPU for calculation).

GPU memory fields:

Why the Processes tab sometimes shows high GPU while the GPU page looks calm: the Processes GPU column shows the busiest engine. The GPU page defaults to one particular engine, such as 3D. Switch the graph to another engine, like Video Decode, and you will see where the work really happens.

Summary