used logic elements increase rapidly!

It sounds like you ran out out of on-chip memory resources and now some FIFOs are being implemented in LEs/ALUTs. I would inspect you on-chip memory utilization to see if you are running low. The DMA has an option where you can force it's internal FIFO into logic instead of RAM. That FIFO is pretty shallow so if you are tight on memory that would be a good one to force into LEs/ALUTs.