See new SAP Note 2857553 – Overall System Performance Degrading After HANA or OS Kernel Upgrade

Reason: With SAP HANA 2 SPS03, the free memory cache (FMC) was introduced in SAP HANA. This feature enables HANA to efficiently reuse the already allocated memory. It has shown significant runtime improvements in many cases.

Workaround:
Disable the FMC by setting configuration parameter on all hosts of the landscape

A complete restart of SAP HANA – including the SYSTEMDB – is required to activate the parameter change.