mysql 5.7 – Performance issues from RDS Aurora 5.6 to Aurora 5.7

Recently upgraded one of my RDS instances to aurora mysql 5.7 from 5.6 and I’ve had to triple the instance class while I try to resolve this (cpu eventually pegs and never declines).

Most reads are slow now (some about 30% slower, others are up to 400% slower). Looking at explain output, the queries are still using proper indexes. innodb_buffer_pool_size us set to default RDS value (instance class*3/24 I think) and most other innodb_* settings are not modifiable.

Here’s an example Mysql5.6:

| count(*) |
+----------+
| 20646739 |
+----------+
1 row in set (0.06 sec)

Mysql5.7:

mysql> select count(*) from nope;                                                                                                                                                                    +----------+
| count(*) |
+----------+
| 20646739 |
+----------+
1 row in set (3.77 sec)

Anyone else encounter this that can provide some insight into some setting I can tweak?