SQL Server AlwaysOn: Lost of heartbeat and connection with secondary replica
why heartbeat was lost?
why connection with secondary replica was lost ?

Depending on which instance of DHS.exe it could be Network Problems or a failure in the local SQL Server instance.

Any workaround ? increase lease timeout, performance of storage or RAM and CPU can help?

Double-check your cluster quorum so that the primary node does not need to communicate with any far-off resources to maintain cluster quorum.
You also have a storage problem that needs to be addressed, but if you use iSCSI or other network-based storage, that might have the same root cause.