Avoiding disk arms with CLOB

I'm facing the need to process a very large amount of data, which is more
than likely going to come in as a SOAP or XML stream but I need to process
this quickly and without losing time with the disk arms if at all
possible.

I know that a clob will allow me to store a larger set of data but from
what I'm reading, you can't just access and read it like a normal
variable.

I assume, and if I'm wrong feel free to slap with a lead pipe, that like
with regular PF's writes are going to cost me time. I know some
individuals don't care about time or say its not important but I need to
return a response in a matter of seconds like 5-8 or lower if possible and
I'm not going to argue that point. It is what it is.

The data coming in if you put it in a PF would have a record length of
somewhere in the 12k range, so you can imagine it'll be larger with XML
tags and that's a single record, whereas we could receive up to 99 lines
with each line in the 12k+ range.

Now, if someone has a suggestion I'm all ears :)