Eclipse is hanged on copy/paste in JavaScript files

I've been running Eclipse Helios 3.6 using the Java/CFEclipse IDEs, and finding some very strange and aggravating errors when trying to edit Javascript files. After the .js file reaches a certain size (~250 lines of code), Eclipse will randomly hang whenever I try to select, copy-paste selections, or save. Clicking after the hang starts will result in the "file edit source ... help" bar being whited out, and clicking again leads to the windows "(not responding)" message displayed in the program header. The hang then goes away after another 5-10 seconds of waiting. This is the case for all JavaScript files I try to edit, although shorter ones don't hang as long and don't bring up the "(not responding)" message.

I've thought it was a problem with the Javascript validation/autocomplete options, and have accordingly turned those off; however, the copy-paste hang problem still persists. I've also tried the Javascript IDE - same problem. Is this a problem with Eclipse Javascript handling, period? Has anyone else gotten errors like these? And if it's a fundamentally Eclipse problem, would anyone be able to suggest a better Javascript/Coldfusion editor?

EDIT: For more information, log output from the latest hang:

!ENTRY org.eclipse.wst.jsdt.ui 4 2 2010-08-18 11:25:54.699
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.wst.jsdt.ui".
!STACK 0
java.lang.NullPointerException
    at org.eclipse.wst.jsdt.internal.compiler.lookup.ArrayBinding.getExactMethod(ArrayBinding.java:233)
    at org.eclipse.wst.jsdt.internal.compiler.lookup.Scope.findExactMethod(Scope.java:401)
    at org.eclipse.wst.jsdt.internal.compiler.lookup.Scope.getMethod(Scope.java:1813)
    at org.eclipse.wst.jsdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:307)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Expression.resolve(Expression.java:477)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.ForStatement.resolve(ForStatement.java:280)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.ForStatement.resolve(ForStatement.java:280)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.IfStatement.resolve(IfStatement.java:191)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolveStatements(AbstractMethodDeclaration.java:337)
    at org.eclipse.wst.jsdt.internal.compiler.ast.MethodDeclaration.resolveStatements(MethodDeclaration.java:139)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:291)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:362)
    at org.eclipse.wst.jsdt.internal.compiler.ast.CompilationUnitDeclaration.resolve(CompilationUnitDeclaration.java:394)
    at org.eclipse.wst.jsdt.core.dom.JavaScriptUnitResolver.resolve(JavaScriptUnitResolver.java:859)
    at org.eclipse.wst.jsdt.core.dom.JavaScriptUnitResolver.resolve(JavaScriptUnitResolver.java:527)
    at org.eclipse.wst.jsdt.core.dom.ASTParser.internalCreateAST(ASTParser.java:862)
    at org.eclipse.wst.jsdt.core.dom.ASTParser.createAST(ASTParser.java:647)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider$1.run(ASTProvider.java:581)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider.createAST(ASTProvider.java:574)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider.getAST(ASTProvider.java:509)
    at org.eclipse.wst.jsdt.internal.ui.viewsupport.SelectionListenerWithASTManager$PartListenerGroup.calculateASTandInform(SelectionListenerWithASTManager.java:150)
    at org.eclipse.wst.jsdt.internal.ui.viewsupport.SelectionListenerWithASTManager$3.run(SelectionListenerWithASTManager.java:135)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)

!ENTRY org.eclipse.wst.jsdt.ui 4 0 2010-08-18 11:25:54.824
!MESSAGE Error in JSDT Core during AST creation
!STACK 0
java.lang.NullPointerException
    at org.eclipse.wst.jsdt.internal.compiler.lookup.ArrayBinding.getExactMethod(ArrayBinding.java:233)
    at org.eclipse.wst.jsdt.internal.compiler.lookup.Scope.findExactMethod(Scope.java:401)
    at org.eclipse.wst.jsdt.internal.compiler.lookup.Scope.getMethod(Scope.java:1813)
    at org.eclipse.wst.jsdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:307)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Expression.resolve(Expression.java:477)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.ForStatement.resolve(ForStatement.java:280)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.ForStatement.resolve(ForStatement.java:280)
    at org.eclipse.wst.jsdt.internal.compiler.ast.Block.resolve(Block.java:89)
    at org.eclipse.wst.jsdt.internal.compiler.ast.IfStatement.resolve(IfStatement.java:191)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolveStatements(AbstractMethodDeclaration.java:337)
    at org.eclipse.wst.jsdt.internal.compiler.ast.MethodDeclaration.resolveStatements(MethodDeclaration.java:139)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:291)
    at org.eclipse.wst.jsdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:362)
    at org.eclipse.wst.jsdt.internal.compiler.ast.CompilationUnitDeclaration.resolve(CompilationUnitDeclaration.java:394)
    at org.eclipse.wst.jsdt.core.dom.JavaScriptUnitResolver.resolve(JavaScriptUnitResolver.java:859)
    at org.eclipse.wst.jsdt.core.dom.JavaScriptUnitResolver.resolve(JavaScriptUnitResolver.java:527)
    at org.eclipse.wst.jsdt.core.dom.ASTParser.internalCreateAST(ASTParser.java:862)
    at org.eclipse.wst.jsdt.core.dom.ASTParser.createAST(ASTParser.java:647)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider$1.run(ASTProvider.java:581)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider.createAST(ASTProvider.java:574)
    at org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider.getAST(ASTProvider.java:509)
    at org.eclipse.wst.jsdt.internal.ui.viewsupport.SelectionListenerWithASTManager$PartListenerGroup.calculateASTandInform(SelectionListenerWithASTManager.java:150)
    at org.eclipse.wst.jsdt.internal.ui.viewsupport.SelectionListenerWithASTManager$3.run(SelectionListenerWithASTManager.java:135)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)