diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index 324401be..17592ccb 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -606,7 +606,7 @@ impl<'a, 'o> Parser<'a, 'o> {
                     fence_length: matched,
                     fence_offset: first_nonspace - offset,
                     info: Vec::with_capacity(10),
-                    literal: Vec::with_capacity(80),
+                    literal: Vec::new(),
                 };
                 *container =
                     self.add_child(*container, NodeValue::CodeBlock(ncb), first_nonspace + 1);
@@ -625,7 +625,7 @@ impl<'a, 'o> Parser<'a, 'o> {
                 let offset = self.first_nonspace + 1;
                 let nhb = NodeHtmlBlock {
                     block_type: matched as u8,
-                    literal: Vec::with_capacity(10),
+                    literal: Vec::new(),
                 };
 
                 *container = self.add_child(*container, NodeValue::HtmlBlock(nhb), offset);
@@ -731,7 +731,7 @@ impl<'a, 'o> Parser<'a, 'o> {
                     fence_length: 0,
                     fence_offset: 0,
                     info: vec![],
-                    literal: Vec::with_capacity(80),
+                    literal: Vec::new(),
                 };
                 let offset = self.offset + 1;
                 *container = self.add_child(*container, NodeValue::CodeBlock(ncb), offset);
@@ -1111,7 +1111,9 @@ impl<'a, 'o> Parser<'a, 'o> {
                         seeked += pos;
                     }
                 }
-                *content = content[seeked..].to_vec();
+                if seeked != 0 {
+                    *content = content[seeked..].to_vec();
+                }
                 if strings::is_blank(content) {
                     node.detach();
                 }
@@ -1152,11 +1154,9 @@ impl<'a, 'o> Parser<'a, 'o> {
                     *content = content[pos..].to_vec();
                 }
                 mem::swap(&mut ncb.literal, content);
-                content.clear();
             }
             NodeValue::HtmlBlock(ref mut nhb) => {
                 mem::swap(&mut nhb.literal, content);
-                content.clear();
             }
             NodeValue::List(ref mut nl) => {
                 nl.tight = true;
@@ -1399,7 +1399,9 @@ impl<'a, 'o> Parser<'a, 'o> {
     }
 
     fn parse_reference_inline(&mut self, content: &[u8]) -> Option<usize> {
-        let delimiter_arena = Arena::new();
+        // In this case reference inlines rarely have delimiters
+        // so we often just need the minimal case
+        let delimiter_arena = Arena::with_capacity(0);
         let mut subj = inlines::Subject::new(
             self.arena,
             self.options,
diff --git a/src/scanners.rs b/src/scanners.rs
index ef37976e..3f84d431 100644
--- a/src/scanners.rs
+++ b/src/scanners.rs
@@ -1,3 +1,14 @@
+/*!
+  In many of these cases the AST will be scanned and then it
+  is found there is no match. In many of these cases the scan
+  turns up False. It can be see that in the very simplest cases,
+  usually by doing a char check at the very begginning of the
+  line, we can eliminate these checks without the same allocations
+  that are done otherwise and cause the program considerable
+  slowdown.
+
+*/
+
 use pest::Parser;
 use std::str;
 use twoway::find_bytes;
@@ -24,6 +35,9 @@ fn is_match(rule: Rule, line: &[u8]) -> bool {
 
 #[inline(always)]
 pub fn atx_heading_start(line: &[u8]) -> Option<usize> {
+    if line[0] != b'#'{
+        return None
+    }
     search(Rule::atx_heading_start, line)
 }
 
@@ -55,11 +69,17 @@ pub fn html_block_end_5(line: &[u8]) -> bool {
 
 #[inline(always)]
 pub fn open_code_fence(line: &[u8]) -> Option<usize> {
+    if line[0] != b'`' && line[0] != b'~' {
+        return None
+    }
     search(Rule::open_code_fence, line)
 }
 
 #[inline(always)]
 pub fn close_code_fence(line: &[u8]) -> Option<usize> {
+    if line[0] != b'`' && line[0] != b'~' {
+        return None
+    }
     search(Rule::close_code_fence, line)
 }
 
@@ -108,7 +128,8 @@ pub enum SetextChar {
 
 #[inline(always)]
 pub fn setext_heading_line(line: &[u8]) -> Option<SetextChar> {
-    if is_match(Rule::setext_heading_line, line) {
+    if (line[0] == b'=' || line[0] == b'-')
+       && is_match(Rule::setext_heading_line, line) {
         if line[0] == b'=' {
             Some(SetextChar::Equals)
         } else {
@@ -121,6 +142,9 @@ pub fn setext_heading_line(line: &[u8]) -> Option<SetextChar> {
 
 #[inline(always)]
 pub fn thematic_break(line: &[u8]) -> Option<usize> {
+    if line[0] != b'*' && line[0] != b'-' && line[0] != b'_' {
+        return None
+    }
     search(Rule::thematic_break, line)
 }