Preview is slow

You see

You open Preview or make an edit that invalidates it. The Generating preview... overlay shows for a long time before the actual preview appears.

What is happening

Plan generation is CPU-bound on complex projects. Lots of geometry, complex fills, many small paths, complex boolean operations, these all take time.

Fix

If you have many objects

• Group objects that always travel together. Smaller object counts plan faster.
• Convert raster-traced paths to clean vector first (the Trace Image dialog has node-reduction options).
• Reduce node counts on imported SVGs that have unnecessary detail.

If you have complex fills

• Coarser scan interval = fewer fill lines = faster plan.
• Reduce passes (re-run preview to compare).
• Consider Offset Fill instead of straight Fill, or vice versa, depending on which is faster on your specific shape.

If raster engravings are large or high-resolution

The raster planner has to compute pixels-to-firing-positions for each pixel. Very large or high-DPI images slow this down.

• Downsample the image to a reasonable size before import (you do not gain quality from resolution beyond your DPI / interval).
• Reduce the line interval if it is finer than needed.

If the machine has slow acceleration

The plan duration calculation runs faster than expected on a fast machine. If your $120-$122 values are conservative, plans take longer because there are more deceleration segments to compute.

This is a minor effect; not usually the main cause.

If your computer is the bottleneck

• Close other heavy apps.
• Reboot if it has been a while.
• Beam Bench is multi-threaded but not infinitely scalable, a fast single-thread CPU helps preview specifically.

Verify it worked

• Preview generates in seconds, not minutes.
• The overlay clears reasonably quickly after edits.

Still stuck?

• Preview dialog reference.
• App is slow on large files troubleshooting.
• Send a feedback report with the slow-to-preview project attached.