Active ComfyUI tab slows down generation process significantly

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [ ] I have custom nodes enabled

### What happened?

Slowdown happen no matter what limiter I'm using (EVEN 1 FPS), or with disabled preview. No matter browser is hardware accelerated (smaller reduction, but still annoying) or not. It just happens. And only this frontend UI is able to slowdown generation. No matter which other website I'm watching - speed of image generation is ok, but if I will try to activate this hellish tab with simplest workflow in existence I have ~30-40% speed reduction. No matter with extra nodes enabled or disabled. I have tested everything and I can't tell why it slows down generation speed so much.

Overall it feels like some script is constantly trying to do something and it's so CPU expensive it can make CPU a bottleneck during generation. Even on heavy websites like CivitAI generation speed is ok (with hardware acceleration disabled or enabled), so it's unlikely the problem related to visualization.

### Steps to Reproduce

1. Just compare generation speed with ComfyUI tab in active and non active states.

### How is this affecting you?

Feature doesn't work as expected

### ComfyUI Frontend Version

1.45.19

### Browser

Firefox

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

OS: CachyOS (the same bug was on Ubuntu as well)
GPU: Intel Arc B580
Workflow: it happens even on starting example

Start by reproducing the comparison in Firefox with the starting example workflow, measuring generation speed while the ComfyUI tab is active versus inactive. Test the reported conditions—preview disabled or limited to 1 FPS, and hardware acceleration enabled or disabled—then profile the active tab to identify the source of the slowdown. Done means generation performance is no longer significantly reduced when the tab is active.

Written by the indexing model from the issue text.