Android Question debug(legacy) problem.

hi erel
when i compile the program in Release mode, it runs fine, but when i try to compile it in debug(legacy) mode i get this error:
"Parsing code. 0.10
Compiling code. 0.21
Compiling layouts code. 0.01
Generating R file. 0.28
Compiling generated Java code. 3.07
Convert byte code - optimized dex. Error
UNEXPECTED TOP-LEVEL ERROR:
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.android.dx.util.FixedSizeList.<init>(FixedSizeList.java:38)
at com.android.dx.rop.code.RegisterSpecList.<init>(RegisterSpecList.java:102)
at com.android.dx.rop.code.RegisterSpecList.withFirst(RegisterSpecList.java:226)
at com.android.dx.dex.code.RopTranslator.getRegs(RopTranslator.java:488)
at com.android.dx.dex.code.RopTranslator.getRegs(RopTranslator.java:453)
at com.android.dx.dex.code.RopTranslator.access$000(RopTranslator.java:48)
at com.android.dx.dex.code.RopTranslator$TranslationVisitor.visitPlainInsn(RopTranslator.java:551)
at com.android.dx.dex.code.RopTranslator$LocalVariableAwareTranslationVisitor.visitPlainInsn(RopTranslator.java:835)
at com.android.dx.rop.code.PlainInsn.accept(PlainInsn.java:80)
at com.android.dx.rop.code.InsnList.forEach(InsnList.java:76)
at com.android.dx.dex.code.RopTranslator.outputBlock(RopTranslator.java:262)
at com.android.dx.dex.code.RopTranslator.outputInstructions(RopTranslator.java:233)
at com.android.dx.dex.code.RopTranslator.translateAndGetResult(RopTranslator.java:212)
at com.android.dx.dex.code.RopTranslator.translate(RopTranslator.java:105)
at com.android.dx.dex.cf.CfTranslator.processMethods(CfTranslator.java:319)
at com.android.dx.dex.cf.CfTranslator.translate0(CfTranslator.java:139)
at com.android.dx.dex.cf.CfTranslator.translate(CfTranslator.java:94)
at com.android.dx.command.dexer.Main.processClass(Main.java:682)
at com.android.dx.command.dexer.Main.processFileBytes(Main.java:634)
at com.android.dx.command.dexer.Main.access$600(Main.java:78)
at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:572)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:170)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:229)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:158)
at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
at com.android.dx.command.dexer.Main.processOne(Main.java:596)
at com.android.dx.command.dexer.Main.processAllFiles(Main.java:498)
at com.android.dx.command.dexer.Main.runMonoDex(Main.java:264)
Optimized dexer failed. Switching to Standard dexer."

what does that mean?