# Objective
- When using `WgpuOptionsPriority::Functionality`, which is the default, wgpu::Features::MAPPABLE_PRIMARY_BUFFERS would be automatically enabled. This feature can and does have a significant negative impact on performance for discrete GPUs where resizable bar is not supported, which is a common case. As such, this feature should not be automatically enabled.
- Fixes the performance regression part of https://github.com/bevyengine/bevy/issues/3686 and at least some, if not all cases of https://github.com/bevyengine/bevy/issues/3687
## Solution
- When using `WgpuOptionsPriority::Functionality`, use the adapter-supported features, enable `TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES` and disable `MAPPABLE_PRIMARY_BUFFERS`
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