I have found that setting the configuration variable MS_REF_NO_CVE_LOAD = 1 works great to reduce cached Drawing Model open times since the underlying reference files are not constantly checking back to the 3D Model. However, it also seems to prevent me from updating and/or synchronising the cached Drawing Model to the 3D Model, as well as switching between Cached and Dynamic modes when using the "Reference visibleedges allmodels synchronizecache", "Reference visibleedges allmodels cache" or "Reference visibleedges allmodels dynamic" keyins.
For example, the only way I can update the cache is to re-attach/re-reference the attachment as Dynamic, and then set it back to Cached. I have also tried reloading the reference attachment after the fact but it doesn't seem to update any settings or view updates. I've found that by using the key-in "reference visibleedges allmodels dynamic" will remove the cache, but then the reference attachment is lost (the name displays red) before it is able to switch back to Dynamic. At that point I reload the reference attachment and can cache the view again. I repeat this after re-loading (or re-attaching) the reference and am then able to access the Visible Edges drop-down list in the Reference dialog box to access the Dynamic, Cached and Legacy options, but after reopening the DGN file that ability is again lost.
When using MS_REF_NO_CVE_LOAD = 1 the reference attachment(s) are intentionally unloaded in the background (without being detached) in order to increase performance. Therefore, this can affect the results when later processes that require the reference attachments, such as the "reference visibleedges allmodels" keyins, are initiated. Following are general guidelines to follow when using MS_REF_NO_CVE_LOAD = 1 along with "reference visibleedges allmodels" keyins:
1. When using the configuration variable MS_REF_NO_CVE_LOAD = 1, first reload the reference file attachment(s) before using any of the keyins. Otherwise you would be attempting to change display modes (Cached or Dynamic) and/or reference settings without having the actual reference data available at the time.
2. If the Drawing remains cached it must be re-synced to match up with the re-loaded reference data.
3. When re-syncing the cache you may also need to update your view window to see any resulting graphic changes.
4. After closing and reopening a DGN file, MS_REF_NO_CVE_LOAD = 1 will again take effect so the reference attachment(s) will be unloaded.