Virtual private servers share a physical host with dozens of other customers. The hypervisor allocates CPU time, memory, and I/O bandwidth according to defined limits, but these limits are theoretical maximums - in practice, hypervisor overhead, memory balloon drivers, and storage contention create variability that applications running predictable workloads cannot tolerate. Benchmarking a VPS in isolation produces impressive numbers. Running it under production load with 40 other customers competing for the same storage bus produces different results.
Bare metal eliminates the hypervisor entirely. Your application runs directly on the physical hardware. CPU cycles are not shared with a virtualization layer. Memory is not subject to balloon drivers reclaiming pages during host pressure. Disk I/O does not compete with adjacent tenants reading the same RAID array. Network I/O does not share a NIC with other VMs through a virtual switch. Every resource is yours for the duration of your service term.
The performance implications are significant for workloads that require consistent latency and throughput. Database engines, real-time analytics platforms, video encoding pipelines, trading systems, and machine learning inference servers all perform measurably better on bare metal than on equivalently spec'd VPS resources. The difference is not the CPU model or the RAM amount - it is the absence of the virtualization overhead and contention that VPS platforms introduce.
Bare metal also enables workloads that are impossible or impractical on VPS platforms. Running nested KVM virtualization to host your own VMs is not possible on most VPS plans. Using hardware-level security features like AMD SEV or Intel TXT requires direct hardware access. Kernel parameter tuning at the hardware level - huge pages, NUMA topology optimization, CPU pinning - requires visibility and control that hypervisor layers abstract away.