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Initial Spell-Checking Delay in RadSpellChecker


Product Version Product Author
2022.3.913 RadSpellChecker for WinForms Desislava Yordanova


RadSpellChecker offers spell check as you type functionality by setting the AutoSpellCheckControl property. A long pause is observed the very first time the spell-checking is used at run time.


The observed slight delay occurs when RadSpellchecker loads the dictionary that is used for spell-checking the words. It actually reads a tdf file that contains all the words for the respective language.

You can choose when this loading time will be performed:

1. Instant loading of the form but wait for the dictionary loading when you start typing for the first time.

2. Slight delay when showing the window to load the dictionary (by setting some initial text inside the AutoSpellCheckControl and then clearing it) but then instant typing in the input box will be available.

The Telerik.WinControls.SpellChecker.Proofing.DocumentSpellChecker that is internally used by RadSpellchecker is implemented with MEF to support dynamic loading of different languages and plugins based model. To support this processing the MEF engine loads the assemblies in the application directory and searches for SpellChecker related interfaces implementation to create / load and activate the spell checker system.

When spell-checking for the first time, the MEF checks all the assemblies, which the control has dependencies to and loads the necessary parts using reflection. However, traversing all the assemblies and searching if there is something to load in them is a slow operation and may decrease the initial spell-checking performance of the RadSpellChecker.

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