The HP 15-1009 is a nice little notebook computer, the only disadvantage being that it has a very slow processor. It's got more than enough RAM to support the integrated Radeon HD 8210 GPU, so your challenge is to do whatever you can to take the processing load off the CPU. For this purpose you need to choose the Ubuntu edition with the most lightweight desktop environment, which is any currently supported version of Lubuntu. 64-bit is faster than 32-bit in most cases. The biggest difference between different releases of Lubuntu is that Lubuntu 14.04 is a Long Term Support release which is supported by updates for three years until April, 2017 and the other releases are regular releases which are only supported for 9 months after the official launch date.
Installing the proprietary graphics drivers for the Radeon HD 8210 GPU shouldn't be a problem. Open the terminal and run ubuntu-drivers devices
to show the Recommended proprietary graphics driver, and then install that one.
The HP 15-1009 is a good notebook with a lot of character. If you conform to the conditions that its hardware dictates, it should perform acceptably. Try QupZilla instead of Firefox. QupZilla is the only lightweight web browser that I have ever used that I consider to be usable on a daily basis. If you also have Firefox installed, you can import your Firefox bookmarks into QupZilla.
QupZilla has renamed itself as Falkon and be installed by the following command in all currently supported versions of Ubuntu:
sudo snap install falkon
Another lightweight application that I recommend is Exaile music player.
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