Opening AutoCAD drawings (.dwg) files in either the AutoCAD Web App or AutoCAD Mobile App may take longer to completely open than opening from inside AutoCAD installed on a computer. Autodesk has released an AutoCAD Web App and AutoCAD Mobile App to allow users the ability to open AutoCAD drawings without having AutoCAD installed or when only a phone or tablet is available. It is possible to modify these drawings but there are limitations compared to full AutoCAD on a computer.
You may experience a delay while opening AutoCAD drawings due to the lack of support files in the AutoCAD Web App and Mobile App compared to full AutoCAD. The delay is typically caused by the substitution of shape files (.shx) and True Type Font files (.ttf) referenced by the drawing.
SHX files, or shape files, are used as text fonts or symbol fonts in a drawing. True Type font files are a type of font file that are available through your computer. AutoCAD drawings require access to the drawing’s source information to properly display the files as intended by the drawing creator. The .shx files and .ttf files are typically installed on the local hard drive with full AutoCAD. There are hundreds of possible .shx and .ttf files that AutoCAD can use. Full AutoCAD will be able to access these files to display the drawing as intended. The AutoCAD Web App and Mobile App are slimmed down versions of AutoCAD and do not have access to all the reference files that may be needed to properly display the drawing. The default behavior of the AutoCAD Web App and Mobile app is to substitute any non-simplex.shx files in the drawing with Simplex.shx.
Currently the AutoCAD Web App only supports the use of the Simplex.shx file. Any other shape files (.shx) or Ture Type Font files (.ttf) in a drawing opened by the AutoCAD Web App will be automatically substituted for Simplex.shx. This is a temporary substitution used to display the drawing through the designated platform and does not permanently change the .shx files in the drawing. When the file is reopened in traditional AutoCAD, the original fonts and .shx files in the drawing will display as intended even when the file has been saved.
If your AutoCAD drawings contain many .shx files then the substitution process could take a few minutes. The only workaround is to use the Simplex.shx font as the default to prevent substitution delays when opening in the AutoCAD Web App.
The AutoCAD Mobile App does have the ability to display other shape files (.shx files) but does not support the use of True Type Font (.ttf). Since the Mobile App operates on a platform with storage, the shape files (.shx) referenced by the drawing and missing from your device can be e-mailed from your computer and saved to your device. Once the shape files are saved on your device, the AutoCAD Mobile App should be able to properly display the shape files as intended by the drawing creator. This process is best outlined in the Autodesk Knowledge link below.