Memory usage of COPY command

When loading (inserting) data into a table with COPY I have read in the
documentation that rows are appended to the end of the table instead of
being added to existing table pages, so I'm wondering about memory
utilization. Our application uses a number of COPY statements in
parallel, so COPY performance is key. Does COPY use the shared buffer
pool, or does it allocate its own block of memory to bulk-load the data
into?

Would tuning shared_buffers in postgresql.conf have an effect on COPY
performance, or is the buffer-pool bypassed altogether on a load?

Thanks,

Keaton