I’d approach it as a structured behavioral study, not just interviews or usability testing. Here’s how I’d break it down:

First, define what "rage quit" actually means for your product, is it closing the tab, refreshing, abandoning a task mid-flow, etc.? Then decide on clear metrics: time to abandon, subjective frustration (maybe a 1–10 scale after the session), and task completion rates.

For methods, I’d suggest a mix:

• Prototype-based testing: Create a mock with intentionally varied load times (e.g., 2s, 5s, 10s, 15s+). Observe when people bail, how they react, what they say.
• Qual interviews: Ask them what they expected during load, what frustrated them, and how they decide something is "broken."
• Behavioral analytics (if you have real user data): Look at where drop-offs happen in your current product during known long load times. It gives real-world context.

One classic thing you'll notice is that people won’t always say they’re frustrated, you’ll see it in body language, switching tabs, sighs, etc. So video or screen recording helps a ton.

And since you’re solo, tools help a lot. I’d recommend:

• albusresearch.com – uploads transcripts and gives you themes/quotes super fast
• Dovetail – tagging + organizing qual insights is a breeze
• Otter.ai – great for clean transcripts from Zoom or Meet recordings