SQL & PL/SQL

Hello All,
I have a table which contains a clob file which holds data in such a fashion as shown below:

col1,col2,col3,col4:col1,col2,col3,col4:col1,col2,col3,col4:col1,col2,col3,col4:ol1,col2,col3,col4... etc etc

basically I have been using a combination of both instr and substr to pull out the data to be parsed as shown below:

col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4
etc etc

However after extensive use it seems to cause massive slowdown, is there another way of doing this which isn't so unwieldy?

NOTE: using vc_arr2 and string_to_table is out of the question as it seems to have a limit to how many rows it can handle.

Any help would be greatly appreciated!

Thanks in Advance!