Yeah, I’ve been there. Honestly, it is SO worth trying the reset before you drop any cash on a replacement. I had an old phone in the same family that was basically unusable, but a fresh start gave it a whole new lease on life. It’s the most cost-effective way to fix those weird glitches. Tbh, these older devices don't have much trade-in value anyway, so you might as well squeeze every bit of life out of it while you can. One thing to keep in mind is that you don't need to worry about the OS. It’s stored on the hardware in a recovery partition, so it just cleans itself up without needing a PC for the reinstall. If things are still slow after the wipe, I’d recommend looking at some of those legacy enthusiast sites like the ones dedicated to mobile developers and hardware fans. They have archived guides on how to turn off certain background features that really help performance on devices with limited RAM. It definitely beats spending three hundred bucks on a new mid-ranger if you can get another six months out of this one!

Regarding what #1 said about "I performed a hard reset on my Lumia", it is a solid first step but keep your expectations realistic. The Lumia 635 hardware is pretty dated now, especially the variants with only 512MB of RAM. If you are pushing the OS with modern web browsing, even a fresh install will struggle. I have a few questions to narrow this down... are you running your apps off a microSD card? If that card is failing or just a slow speed class, it'll cause those crashes even after a hard reset. Also, are you on Windows Phone 8.1 or did you upgrade to the Windows 10 Mobile technical preview? Basically, if the reset fails, you are likely looking at a hardware limitation rather than a software bug. Performance issues on these older units are often tied to the low memory overhead. Since it has zero trade-in value, trying the reset is free, but dont expect it to handle modern web tasks smoothly. TL;DR: The reset clears system junk, but check if a slow SD card is causing the lag before you wipe the internal storage.

I performed a hard reset on my Lumia 635 last month with good results. The process is straightforward but does wipe everything, so back up your data first using the Windows Phone app on your PC.

For the actual reset, you have two options. The simplest is through Settings > About > Reset Your Phone. If your phone isn't responding, use the hardware method: power off completely, then hold Volume Down + Power until you feel a vibration. Release Power but keep holding Volume Down until you see a "!" on screen. Then press Volume Up, Volume Down, Power, and Volume Down in sequence.

After reset, your phone will restart with factory settings. You'll need to sign in with your Microsoft account to restore some basics, but apps will need manual reinstallation.

In my experience, this fixed most performance issues for about 2-3 months. The 635 has limited RAM (1GB), so it will eventually slow down again as apps become more demanding. I'd recommend the reset, but also start researching replacements, as Microsoft has discontinued Windows Phone support.

Make sure to save your photos, contacts, and text messages beforehand—these are the hardest to recover if not backed up properly.