GPU load is high when emulation is idle

### Describe the bug

The GPU (of my PC) load is about 10% when the game is running, but it's always about 50%~60% when emulator status is idle (emulation is paused or even rom has not been loaded).

I think the higher GPU load when idle is an issue for me.

**When I'm dragging the emulator window (move the window position or change the window size), the GPU load is 0.**

### Expected behavior

When emulation is idle, GPU load should be low.

### Steps to reproduce the bug

1. Don't load game rom, or pause the emulation.
2. Check GPU load on PC.

### Operating System

Windows 10

### PCSX-Redux version

Version: 19850.20240922.1.x64
Build: 92
Changeset: 6ec5348058413619b290b069adbdae68180ce8c0
Date & time: 2024-09-22 09:04:11

### CPU model

AMD Ryzen 5 3600

### GPU model & Drivers

Vendor: NVIDIA Corporation; Renderer: NVIDIA GeForce GTX 1650/PCIe/SSE2; Version: 3.2.0 NVIDIA 551.86; Shading language version: 1.50 NVIDIA via Cg compiler; Texture units: 32

### BIOS version

openbios

### Options

- [ ] Dynarec CPU
- [ ] 8MB
- [ ] OpenGL GPU
- [ ] Fastboot
- [X] Debugger

### Iso checks

_No response_

### Logs

```
Loading memory card C:\Users\tt\AppData\Roaming\pcsx-redux\memcard1.mcd
Loading memory card C:\Users\tt\AppData\Roaming\pcsx-redux\memcard2.mcd
PCSX-Redux booting
Copyright (C) 2019-2024 PCSX-Redux authors
CPU type: Interpreted
Loaded BIOS: E:\game\pcsx-redux\openbios.bin
OpenBIOS detected (7fc4f078)
```

### Additional information

running:

idle:

Reproduce the issue on Windows 10 with PCSX-Redux 19850.20240922.1.x64, comparing GPU load while emulation is running, paused, unloaded, and while dragging or resizing the window. Trace the emulator's desktop rendering and idle event handling; done means idle or unloaded states no longer sustain roughly 50–60% GPU load while normal rendering remains functional.

Written by the indexing model from the issue text.