Shared or dedicated vCPU?

Cloud servers and VPS almost always come with a number like "4 vCPU". But the same number can mean very different performance – depending on whether you share the cores with others or they're reserved for you.

What a vCPU is

A vCPU is a virtual processor core that the provider assigns to your server. It usually corresponds to one hardware thread of a physical processor, not a full core. Many virtual servers run side by side on one physical machine.

Shared vCPU

With shared vCPUs, several customers share the cores. Providers hand out more vCPUs than physically exist, because most servers compute very little most of the time.

• Pro: much cheaper.
• Con: when your neighbors are busy, you get less. Performance varies.
• Good for: websites, small shops, development and test environments, VPN, monitoring, bots – anything that mostly waits and computes in short bursts.

Dedicated vCPU

With dedicated vCPUs, the cores are reserved for you. Nobody else runs on them.

• Pro: consistent, predictable performance.
• Con: costs more.
• Good for: databases under load, build and CI servers, video encoding, game servers, applications with steady high CPU usage.

How to tell what you get

Many providers put it in the name or the product description. At Hetzner, for example, the CCX types are dedicated, the CPX types shared. In our cloud comparison every card says so ("shared cores" or "dedicated cores"), and the vCPU type filter lets you search for it.

Checking whether your server is slowed down

On Linux, the "st" (steal time) value in top or vmstat 1 shows how much CPU time the host is currently withholding because others are using it. A few percent is normal with shared vCPUs. If it stays high and your application is noticeably slow, a type with dedicated vCPUs is the fix.

Rule of thumb

Start with shared vCPUs if your application mostly waits for requests. Switch to dedicated vCPUs once CPU load stays high or fluctuating response times hurt. If even that gets too expensive, consider a whole physical server: Cloud server or dedicated server?