I was surprised that I couldn't find something like this already, so please let me know if I missed it.

This mod will provide a cinematic effect by slowing time reflexively in certain combat situations. It also provides options so it can be used as a lightweight combat overhaul with a cinematic feel.

This mod causes time to slow in the following situations:

When an enemy power attacks the player
When an enemy of the player is staggered within 7 feet
When the player drops into a crouch while charging a spell
When an enemy searching for you comes within 7 feet

By default the effect is strictly cosmetic. However, there are additional options in the MCM that can be used to turn slowed time to your advantage.

Note that two of these effects are dependent on perks, which means that they may be overridden by other perks that do similar things. For example, the vanilla Reflexes perk will take precedence over this mod's. The vanilla one is better anyway, so you want that. The perks in this mod have a deliberately low priority to allow perks that you have actually chosen from the perk trees to override them whenever possible.

There is an option make slow time grant automatic crits from bladed weapons and a chance of knockdown from blunt weapons, for people who want some tangible benefit from slowed time.