Poor Revit model performance is rarely the machine's fault. Most of it comes from what accumulates inside the file: warnings piling up, families never once placed, draft views left behind, every link loaded at once.
This article shows how to find those, clear them in the right order, and what to do once a file is already damaged. To learn modelling and documentation end to end, see the Revit Architecture course.
Seven common reasons a Revit model runs slowly
| Cause | What to do |
|---|---|
| Too many views open | Every open view is another region to redraw. Use Close Inactive on the View tab |
| Detail level too high | Fine on a wide view forces Revit to draw every construction layer. Work at Coarse |
| 3D trees and people | Image-heavy families slow down every operation |
| Nested groups | A group inside a group makes every edit recalculate several times over |
| Every link loaded | Unload the links you do not need to see |
| Accumulated warnings | Each warning is a constraint Revit re-checks after every change |
| Shadows left on while modelling | Turn Cast Shadows off unless you are producing imagery |
The last two deserve most attention because few people think of them. Shadows left on mean every orbit is recomputed, and warnings quietly accumulate.
Unloading links is covered in linking Revit models, and nested groups in groups in Revit. Autodesk gathers its performance advice on Memory Usage and Instability.
Revit review warnings: a list that only ever grows
Revit records every warning the user has dismissed. That list never shortens by itself, and a model carrying a few thousand warnings is both slow and hard to trust.
Both commands live on the Manage tab, Inquiry panel.
| Command | What it does |
|---|---|
| Select by ID | Paste an element id and Revit selects that exact element |
| Review Warnings | Opens the list of every warning in the model |
| No. | Component | What it means |
|---|---|---|
| 1 | The warning tree | Grouped by message. Expand a branch to see each individual case |
| 2 | Three buttons | Show jumps to the element; More Info explains further; Delete Checked deletes the ticked elements |
| 3 | Export and Close | Export writes the list to a file so several people can share the work |
Delete Checked deletes elements, not warnings. Read carefully before clicking: most warnings are cleared by correcting the model, not by deleting what it contains.
The dialog does not lock the screen. Most view navigation still works while it is open, so the list can be read while orbiting the model. Autodesk documents the command on Review Warning Messages.
Sorting warnings by how serious they are
Not every warning is worth the effort. Three groups make the order of work obvious.
| Level | What belongs in it |
|---|---|
| Fix now | Overlapping elements, unenclosed rooms, orphaned components. These make quantities and drawings wrong |
| Should fix | Unsatisfied constraints, duplicated elements. These slow the model and make later edits harder |
| Can wait | Overlapping tags, text running out of its box. These affect only the sheet and are settled at layout |
| No. | Component | What it means |
|---|---|---|
| 1 | The first two warnings | Elements that join but do not intersect, and one element wholly inside another. The two commonest geometric faults |
| 2 | Overlapping areas | Area and perimeter collapse into one region while the others read Redundant. Schedules are wrong as a result |
| 3 | The Export and Close buttons | Export writes the whole list out. On a large project this is the only way to share the fixing between several people |
On a large model the warning list never quite reaches zero. The model manager's job is to keep it short, and free of the faults that corrupt numbers.
The cheapest routine is a weekly slot: open Review Warnings and clear the fix-now group. Fifteen minutes a week costs far less than three days spent cleaning a model that has reached two thousand warnings.
Purge Unused in Revit, and the number 1160
A model grows heavier as it goes, and most of that weight is material never used. Purge Unused, on the Manage tab, Settings panel, clears it out.
| No. | Component | What it means |
|---|---|---|
| 1 | Views | Unused views. The 2027 release folds views into the purge list, not only families as very old releases did |
| 2 | Families | Families and types never once placed in the model. This is most of the list |
| 3 | Number of items checked | How many entries are ticked. On an almost empty test project the figure was already 1160 |
That number is worth remembering: it is everything the template carries that nobody has used. A real project of a few months usually carries considerably more.
The command is safe — only unconstrained, unused entries can go. But it also removes types you were deliberately keeping, so clear their ticks before clicking OK.
Run it three times over: the first pass removes unused families, which in turn leaves some materials and types unused, so a second pass still finds more. Autodesk also advises backing the file up first, on Purge Unused Objects.
The shortcut is PU, from the same group as ML and IF in Revit keyboard shortcuts.
Six steps to reduce Revit file size, in order
The order matters more than any single command. Purging before the warnings are fixed wastes most of the effort.
- Open Review Warnings and clear the fix-now group.
- Delete draft views no longer in use, and abandoned sheets.
- Unload the links you no longer need to see.
- Run Purge Unused, clearing the ticks on types you want to keep.
- Close the file and reopen it through Open with the Audit box ticked.
- Record the file size before and after, to learn whether the cleaning worked.
Step 6 is the one usually skipped. Without measuring, next time you still will not know which step earned its time.
Audit a Revit file, and how often to run it
| No. | Component | What it means |
|---|---|---|
| 1 | Audit | Makes Revit check the whole file structure and repair what it finds while opening. Far slower than a normal open |
| 2 | Worksharing | Detach from Central and Create New Local, active only on a workshared file |
Audit is the first move whenever a file behaves oddly: very slow to open, an error on saving, or one view that refuses to open. Run it, save, and most cases are settled.
On frequency there are two different recommendations, and both are worth knowing. Autodesk advises a weekly audit, more often on a fast-changing model, on Best Practices: Preventing Data Corruption. The practice taught at the Institute is narrower: run it on symptoms and before each major issue, because an audit is slow and does nothing for a healthy file.
Recover a corrupt Revit file from a backup
On every save, Revit keeps the previous version as a backup in the same folder, its name carrying a sequence number. How many are kept is set in Save As, under Options.
Backups rescue more files than anything else: rename a backup to .rvt and it opens as an ordinary project.
| Symptom | Treatment |
|---|---|
| Unusually slow to open | Recoverable. Run Audit, then Purge Unused |
| One view errors when opened | Usually recoverable. Delete that view and rebuild it |
| Revit quits while opening the file | Try the most recent backup. If that is damaged too, step further back |
| File truncated by a power cut mid-save | Usually not recoverable. Use a backup |
| Saved by a newer Revit release | Cannot be opened by an older release, and there is no way to downgrade |
That last row is why a team must agree one Revit release at the start of a project. One person upgrading and saving forces everyone to follow, with no way back.
Try it: clean a model and measure the result
A thirty-minute exercise. It works through Revit model performance end to end; use a copy of a real model, never the live file.
- Record the file size before starting.
- Go to Manage, Inquiry panel, click Review Warnings. Note the total.
- Sort them into the three severity groups, then clear the fix-now group.
- Click Export to save the remaining list to a file.
- Delete draft views and unused sheets.
- Go to Insert, Manage Links, and unload the links you do not need.
- Run Purge Unused, note the Number of items checked, then click OK.
- Run it a second and third time, noting the figure each time.
- Close the file, reopen through Open with Audit ticked, then save.
- Record the final file size and compare it with step 1.
Step 8 shows most clearly why the command has to be run repeatedly: the second figure is rarely zero.
Frequently asked questions
Can Purge Unused delete something I am using?
No. It removes only unused, unconstrained entries. It does remove types you were deliberately keeping, so clear their ticks before clicking OK.
Should I audit the file every day?
Autodesk recommends a weekly audit. In practice, running it when the file shows symptoms and before each major issue is enough, because an audit is slow.
Can I clear warnings with Delete Checked?
Better not. That button deletes elements rather than warnings. Most warnings are cleared by correcting the model.
A file was saved in a newer Revit release. How do I open it in an older one?
You cannot, and there is no downgrade path. Someone with the newer release has to export an intermediate format.
Related articles
- Linking Revit models — unloading links and managing paths
- Groups in Revit — why nested groups slow a model down
- Revit keyboard shortcuts — PU, ML and IF, and the hide/isolate keys
- How to create a family in Revit — building lean components so the model stays light