Why does single-tenancy matter for performance?
Because virtualisation is never free, and sharing is never invisible. The
numbers below are the difference between a machine that performs the same
every hour and one whose speed depends on strangers.
5–15%A hypervisor consumes roughly 5–15% of CPU and RAM for itself before your workload runs.
10–30%Compute-intensive workloads commonly run 10–30% faster on bare metal than on equivalent cloud VMs.
50–100µsLocal NVMe answers in roughly 50–100 microseconds; network-attached cloud block storage typically sits at 200–500 microseconds, with higher tail latency.
1:1Cloud vCPUs are time-shares on shared cores and are often oversubscribed (ratios such as 8:1 are documented); on bare metal the physical cores are yours, 1:1.
The noisy-neighbour problem is the other half. On shared hosts, another tenant can degrade your CPU, memory bandwidth, network, and storage I/O without warning.
Cloud platforms add credit systems and bandwidth caps to limit the blast
radius, but the contention is structural — you are paying for isolation you
do not fully have. Single-tenancy removes the question entirely, and with
it a whole class of risk: Single-tenancy means physical isolation, removing the class of hypervisor-escape and side-channel risks that exist in multi-tenant environments.
Cost follows performance here rather than fighting it. For identical specifications, bare metal frequently runs 50–70% cheaper than the equivalent hyperscaler instance, before data-egress charges.
The savings are largest exactly where cloud is most expensive — sustained,
predictable load and high data egress — which is the profile of most
production systems once they settle.
The same logic runs through memory and cache. A virtual machine's memory
can be reclaimed by the hypervisor under pressure, and its bandwidth is
shared with whatever else lives on the host; on bare metal the full memory
bus is yours, and NUMA placement is something you control rather than guess
at. For workloads that stride across large datasets — analytics, in-memory
caches, big database working sets — that steady, uncontested bandwidth is
often worth more than raw clock speed.
Consistency is the quiet benefit underneath the headline numbers. Averages
rarely hurt you; tail latency does. A shared host can serve a fast average
and still spike at the ninety-ninth percentile when a neighbour gets busy,
and those spikes are exactly what a user notices or an SLA punishes. A
machine you do not share has far less to spike about, which is why
latency-sensitive systems keep coming back to it.