will increasing swap memory change how fast my computer runs?

Sure it would be useful for your computer, The best size is the double of your RAM size so more then 512Mo would be useless

so how do i delete the file?

No, since priority is using RAM, this
> 256mb of RAM memory
is very less.
https://help.ubuntu.com/community/Installation/SystemRequirements

You may consider upgrading RAM or minimal installation.
https://help.ubuntu.com/community/Installation#Minimal%20installations

https://help.ubuntu.com/community/SwapFaq

can i change priority use a flash drive as ram(because flash memory is usually faster then hard memory)

You need xubuntu:

The goal of Xubuntu is to produce an easy to use distribution, based on Ubuntu, using Xfce as the graphical desktop, with a focus on integration, usability and performance, with a particular focus on low memory footprint. The integration in Xubuntu is at a configuration level, a toolkit level, and matching the underlying technology beneath the desktop in Ubuntu. Xubuntu will be built and developed as part of the wider Ubuntu community, based around the ideals and values of Ubuntu.

http://www.xubuntu.org/

http://en.wikipedia.org/wiki/Random_access_memory

i have 1 gb of ram and 512 mb of swap
i read a lot about double size of swap and think - it's just a joke
at startup my ubuntu use 140mb of ram, 0 of sawp
after two hours working (dc+torrent+firefox something downloading, qutim, audio/movie) it uses up to 300 mb of ram and up to 150 mb of swap.
why do i need double-sized swap? for hibernation you need swap almost equivalent used ram (a bit more) - that's enough

Alright so let's clear up some things here :D swap will take a much
significant effect if you had a ram of let's say size 512 mgs. if you
guys have ram of 1 gib or more than just leave swap as it is. Its not
bothering anyone so it should be left as such. Trying to change swap
could cause a little trouble or regressions, neither of which you want
:D

Regards,
Vikram Dhillon

~~~
There are lots of Linux users who don't care how the kernel works, but
only want to use it. That is a tribute to how good Linux is.
-- Linus Torvalds

On Mon, Dec 21, 2009 at 2:23 PM, Raiden
<email address hidden> wrote:
> Question #94294 on yelp in ubuntu changed:
> https://answers.launchpad.net/ubuntu/+source/yelp/+question/94294
>
> Raiden proposed the following answer:
> i have 1 gb of ram and 512 mb of swap
> i read a lot about double size of swap and think - it's just a joke
> at startup my ubuntu use 140mb of ram, 0 of sawp
> after two hours working (dc+torrent+firefox something downloading, qutim, audio/movie) it uses up to 300 mb of ram and up to 150 mb of swap.
> why do i need double-sized swap? for hibernation you need swap almost equivalent used ram (a bit more) - that's enough
>
> --
> You received this question notification because you are an answer
> contact for Ubuntu.
>