OPPO’s ColorOS sends diagnostic data to Chinese servers by default. Custom ROMs like LineageOS or GrapheneOS (unofficial) block telemetry completely.
Once you flash a custom ROM, your warranty is void (though likely expired anyway). You also cannot use OPPO’s recovery tools.
Custom ROMs (such as Pixel Experience, LineageOS, or Evolution X) are typically stripped down to the essentials. They remove carrier bloatware and unnecessary manufacturer apps. This results in a "lighter" operating system that feels snappier. Animations are often faster, and the MediaTek Helio P70 processor is allowed to manage resources more efficiently without heavy proprietary overlays slowing it down.
For the average user who just wants a phone that works, sticking with the final official ColorOS version is simpler but not better. For the enthusiast, developer, or anyone frustrated by lag, expired security patches, and software limitations, a custom ROM is unequivocally superior. The OPPO A91’s hardware still has years of life left, but its software has been abandoned by its manufacturer. By installing a custom ROM, you transform a forgotten mid-ranger into a fast, modern, secure, and private device. The process demands patience, but the reward—a better phone than OPPO ever delivered—is worth the effort. If you own an A91 and feel its age, do not buy a new phone. Reflash its soul instead. oppo a91 custom rom better
I understand you're looking for a custom ROM for the OPPO A91 (model code: CPH2001/CPH2021) to get a better experience.
However, I need to give you an important reality check first:
Since you can't install a true custom ROM, here are better ways to improve your OPPO A91: OPPO’s ColorOS sends diagnostic data to Chinese servers
| Option | What It Does | Difficulty | |--------|--------------|-------------| | Debloat with ADB | Remove bloatware without root (disable unwanted OPPO/Google apps) | Easy | | Install GSI (Generic System Image) | Experimental Android 13/14 GSIs might work, but with bugs (camera, fingerprint issues) | Hard | | Use a Third-Party Launcher | Nova Launcher, Lawnchair, or Niagara for a stock Android look/feel | Very Easy | | Disable Animations | Increase perceived speed via Developer Options | Very Easy | | Replace Stock Apps | Use Google Phone/Contacts/Messages instead of OPPO apps | Easy |
To understand why a Custom ROM is better, one must first identify the shortcomings of the stock software on the A91:
Yes—installing a well-supported custom ROM can improve performance, battery life, privacy, and update longevity compared with the stock ColorOS on an Oppo A91 (a.k.a. Realme 5 Pro / similar MediaTek/Snapdragon variants depending on region). Benefits depend heavily on which ROM you pick and how you install it. You also cannot use OPPO’s recovery tools
The most immediate benefit of a custom ROM on the OPPO A91 is a dramatic performance improvement. ColorOS, while feature-rich, is notoriously heavy. Background processes, aggressive RAM management, and UI animations consume resources that could be better used for your apps. Custom ROMs such as LineageOS, Pixel Experience, or crDroid are built on AOSP (Android Open Source Project) and are remarkably lean.
By stripping away unnecessary services, a custom ROM can make the Helio P70 feel snappier. App launch times decrease, scrolling becomes smoother, and the dreaded “jank” that appears after months of use virtually disappears. Users often report that an A91 running a lightweight Android 13 or 14-based ROM feels faster than it did on its original Android 9 or 10 firmware. The phone’s 8GB of RAM is finally allowed to work efficiently without being constantly occupied by background telemetry and vendor services.