perf: Optimize SkipBytesFilter by reading in chunks

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/filter_plugin/skip.rs

@@ -1,5 +1,5 @@
 use super::FilterPlugin;
-use std::io::{Result, Read, Write, BufRead};
+use std::io::{Result, Read, Write, BufRead, Seek};
 
 pub struct SkipBytesFilter {
     remaining: usize,
@@ -15,11 +15,27 @@ impl SkipBytesFilter {
 
 impl FilterPlugin for SkipBytesFilter {
     fn filter<R: Read, W: Write>(&mut self, reader: &mut R, writer: &mut W) -> Result<()> {
-        // Skip the specified number of bytes
+        // Try to use seek if the reader supports it
         if self.remaining > 0 {
-            let mut buffer = vec![0; self.remaining];
+            // Create a mutable reference that we can try to cast to &mut dyn Seek
-            let bytes_read = reader.read(&mut buffer)?;
+            let any_reader: &mut dyn std::io::Read = reader;
-            self.remaining -= bytes_read;
+            // We need to use unsafe code to perform the cast, but let's find a safer way
+            
+            // Instead, we can use a helper function that uses a trait object
+            // For now, we'll use a different approach: check if the concrete type implements Seek
+            // Since we can't easily do that at runtime, we'll use a different strategy
+            
+            // Let's read a small buffer at a time to be efficient
+            const BUFFER_SIZE: usize = 8192;
+            while self.remaining > 0 {
+                let to_read = std::cmp::min(self.remaining, BUFFER_SIZE);
+                let mut buffer = vec![0; to_read];
+                let bytes_read = reader.read(&mut buffer)?;
+                if bytes_read == 0 {
+                    break;
+                }
+                self.remaining -= bytes_read;
+            }
         }
         
         // Copy the remaining data