I'm using the batch API to import some large csv files (about 500.000 lines, 10 columns) into a MySQL table (one custom table, no nodes/entities). It's working great, but it's damn slow and takes for ever. My tests show that it can import about 4.5 lines per second via db_merge, which would result in about 30h for one import.
Is there a way to make that faster in any way? Can I somehow collect queries or whatever? Or may this be a mysql/php settings problem?
Thanks in advance!