Implementing a high-resolution timer helps in accurately measuring the time between frames. This is essential for fast-moving objects to ensure that the distance they travel between frames is calculated precisely.

Depends on the engine or if you're writing the detection yourself. Use one/some of these. Continuous Collision Detection, Ray Casting, Shape Casting, Temporal Coherence, Sub-Stepping.

Increase the timer precession is tricky. The more you higher it the more performance impact will occur. You should first consider edit timer precession when all other solution are failed. Change rigid body calculation to "dynamic continue" and use thick double size collision mesh that is simplified enough so the physics can be calculate easier and with high precession. If that failed then tweak the timer precession only a very little and test.

Continuous collision detection involves checking for collisions at multiple points along an object's trajectory, rather than just at its starting and ending positions. This helps in identifying collisions that might occur during high-speed movements, reducing the likelihood of objects passing through each other.

Using continuous collision detection is also performance expensive, make sure to use it when necessary, change collision detection type when the physics object is far enough to reduce the impact of performance, disable the physics for the object that is far from the player and camera, implement the physics lod concept this way. Make sure also the collision mesh are optimized and double sided and thick enough to make physics calculation accurate and minimize its impact on the performance overall.

Implementing bounding volumes, such as bounding boxes or spheres, around objects can simplify collision calculations. Combining this with spatial partitioning techniques called Bounding Volume Hierarchy which can significantly reduce the number of potential collision checks, optimizing performance for fast-moving objects.

Fine-tuning physics parameters like gravity, friction, and restitution can impact how objects respond to collisions. Adjust these settings to strike a balance between realism and stability, especially when dealing with high-speed movements.

Simplified double sided and thick collision meshs, change rigidbody physics type as necessary, Disable physics on object that don't need it. implement the idea of lod in physics engine. Tweak the timer precession only if necessary. That is the most needed points to adjust and optimize physics.

Regularly test and debug your collision detection system, especially with fast-moving objects. Use scenarios that simulate various speeds and directions to ensure the accuracy and reliability of your collision detection algorithms.

In Unity, you may encounter issues where fast-moving objects fail to collide with each other and instead pass through. This issue can be resolved by changing the collision detection mode from ‘Discrete’ to ‘Continuous’. Alternatively, you can decrease the fixed timestep by navigating to ‘ProjectSettings/Time’. The default value is 0.02 seconds. By slightly reducing this value, FixedUpdate() will execute more frequently, leading to more frequent collision detection. This adjustment will also result in a smoother game experience.

Implementing interpolation techniques can enhance collision detection accuracy by estimating an object's position between two frames. This is particularly useful for fast-moving objects, where traditional collision checks might miss interactions due to the object's high speed.

It completely depends on your 3D scene, especially the shapes of objects, and also on the power of your CPU/GPU on your target devices. There are many algorithms including but not limited to: 1. BVH 2. Octree 3. SAP 4. Hash Grid 5. GJK 6. Spatial Hashing 7. Moller Trumbore and etc.