# Slowness · Crashes · Performance

Scope

Slow, laggy, crashing. For "the command does nothing", see Commands Not Working.

# Quick reference

Symptom	Cause	Fix
Framing / ceiling generation takes ages	One very large area generated at once	Work in zones — don't do a whole floor in one go
Library opens slowly, scrolling stutters	Thumbnails pulled over the network	Normal, cached once; scroll more slowly
C: drive full	Library cache accumulates on C:	Clear cache (see Family Library)
Realistic mode makes the model unusable	Realistic mode is extremely compute-heavy	Don't leave it on — switch in only to check textures
Gradient / random curtain wall times out	Panel sizes too small — too many cells	Increase the sizes
Display glitches, lines getting blurry, random ghosting	Graphics driver misbehaving	Restart Revit; if it persists, update/roll back the GPU driver
Repeated freezes	Add-in conflict	See Commands Not Working

The most common cause of slowness

Don't draw an enormous slab (the classic new-user mistake) — framing counts grow multiplicatively.

All framing generation should be done zone by zone
Ceilings likewise: don't create in a 3D view — creating on the correct work plane is both more accurate and faster
Gradient / random curtain walls: don't set panel sizes too small, or responses take a long time

Realistic mode is required to see textures
But it places extremely high demands on compute, and bogs down once a project grows
Recommendation: switch into Realistic only to verify texture replacements, then switch back

If things get progressively worse (blurry lines, random ghosting, display corruption) → restart Revit first
If that doesn't help → check your graphics driver
On shared machines, input method / GPU driver / add-in conflict are the three most common culprits

Remove add-ins you don't use — reduces conflict probability (see Commands Not Working)
Clean up project junk — use "junk cleanup" (sections / unused items / materials), "remove duplicates", "ungroup all" and "clean family parameters" so junk doesn't accumulate

Clean families too

Not just project files — families also need cleaning, or they grow heavier with every use.