There are several things that can impact performance on "traditional" container runtimes. For example, cgroups, LSMs, seccomp (especially with spectre mitigatio

There are several things that can impact performance on "traditional" container runtimes. For example, cgroups, LSMs, seccomp (especially with spectre mitigations), network NS/bridges, etc. There are also more subtle things like being able to do CMA, or deal with shared memory. Most runtimes let you opt out but this becomes difficult to manage and secure with multiple users.