Configuration MySQL 5.7

[Valy Ion]

Hi, can you help me? I worked on a MySQL 5.5 server. I saved the database. I uninstalled version 5.5 and I installed 5.7. I restored the database and started working. I find that 5.7 is much faster than 5.5 but to my amazement 2-3 times slower to write !? I use the following settings at a total of 32 GB RAM: : innodb_buffer_poll_chunk_size=2G, innodb_buffer_poll_size=42G, innodb_log_file_in_group=2, the other settings are the default ones. I haven't been able, I probably don't know, to set the innodb_log_file_size correctly. What should I do, where am I wrong?