DRS Optimizations

Currently, the KVM DRS balanced algorithm evaluates every possible VM-to-host combination multiple times and each evaluation triggers the full deployment planning logic (affinity checking, capacity calculation, tag matching, etc.). It also depends on how imbalanced are the clusters, making it progressively slower when the imbalance is higher. So it could take more than 30 minutes to process about 300 VMs, rendering it practically unusable for bigger environments with thousands of VMs.