UIWebView loads a local file for a long time

Question

I have a UIWebView which loads .rtfd.zip files like this:

-(void)viewWillAppear:(BOOL)animated {
self.title=@"Title";
if(rowPosledovatelnosti==0) {
    [self loadFile:@"PosledovatelnostiObzie.rtfd.zip"];
}
if(rowPosledovatelnosti==1) {
    [self loadFile:@"Arifmeticheskaya.rtfd.zip"];
}
if(rowPosledovatelnosti==2) {
    [self loadFile:@"Svojstva_Arifmeticheskoj.rtfd.zip"];
}
if(rowPosledovatelnosti==3) {
    [self loadFile:@"Geometricheskaya.rtfd.zip"];
}
if(rowPosledovatelnosti==4) {
    [self loadFile:@"Predel_Posledovatelnosti.rtfd.zip"];
}
if(rowPosledovatelnosti==5) {
    [self loadFile:@"Summa_Geometricheskoy.rtfd.zip"];
}

}

But on the device it takes some time for the UIWebView to load the content. Is there any way to optimize the loading time?