how to speed up slow laptop?

that's kind of a difficult thing to do since that laptop was never intended to be a high performance machine... there are a few things likely holding it back. First is the processor (which you can't do anything about). Since it is using integrated graphics that means that the cpu is responsible for doing absolutely everything (running both tasks as well as driving the monitor). This is normally okay if you have a laptop with an i3 - i7 or something like that but a celeron was never intended to drive an entire laptop and perform well in all applications. For basic performance tasks it's probably fine but it would never be expected to game or even do heavy multi-tasking. Upgrading the hard drive to an SSD could help performance but buying an SSD is likely out of the question considering what you paid for the laptop in the first place.

My only recommendation would be try buying a 4GB stick of RAM (from what I read your laptop only has 1 slot for RAM) and try to get one with a higher clock speed (1600 MHZ and up). Reason for this is since all applications and the display share the same RAM that is likely bottlenecking your computer at the moment. Especially if you get a few programs open at the same time, it can be quite easy to use up 2 GB of RAM (heck on my laptop I use 4 GB without even realizing it usually and I have a dedicated graphics card). Getting that extra 2 GB of RAM will just allow you that much more headroom (and it sounds like it may help). Also, the reason why I said look for faster memory is because it is being used to drive the display as well and it is really recommended to have fast RAM for graphics.

Things you could try doing that don't cost money could include using a lighter web browser (i.e. not chrome pick one that uses as little RAM as possible), don't leave programs open in the background if you're not using them, don't place gadgets or widgets (whatever they call them on windows) on your desktop because they eat up your RAM and CPU like nothing else, and just do anything possible to keep your usage of RAM down.

Remember, you computer was not intended to be a high performer, so trying to make it one probably isn't the best idea. The extra RAM will help but honestly if you need alot more performance then I would suggest returning the laptop you have and getting a more powerful one (or drop linux on your current laptop but I'm assuming that's out of the question as well).

Hope you find this helpful