matlab-scan.el:

(matlab-scan-previous-line-ellipsis-p):
Use `parse-partial-sexp' instead of `syntax-ppss' b/c
for ellipsis, we only need to check from bol, and parens
and comments can be ignored.

matlab.el:
(matlab-line-count-open-blocks, matlab-line-count-closed-blocks):
Update to accept 2 lvl1 context for the start and end of the block searches.
Use these to bound the search, and avoid creating more contexts, and avoid
calling `matlab-scan-beginning-of-command'.
(matlab-next-line-indentation):
Be careful about calls that require syntax to propertize the buffer.
Starting with input lvl1, capture lvl1 ctxt for beginning of command
and use that for remaining calls.  This makes it more explicity about
what is being checked where, and faster.

matlab-scan.el

@@ -804,7 +804,11 @@ This is true iff the previous line has an ellipsis."
     (beginning-of-line)
     (when (not (bobp))
       (forward-char -1)
-      (let* ((pps (syntax-ppss (point)))
+      ;; Ellipsis scan always resets at BOL, so call non-cached
+      ;; `parse-partial-sexp' instead of regular `syntax-ppss' which
+      ;; can be slow as it attempts to get a solid start from someplace
+      ;; potentially far away.
+      (let* ((pps (parse-partial-sexp (point-at-bol) (point-at-eol))) ;;(syntax-ppss (point)))
 	     (csc (nth 8 pps)))
 	;; Ellipsis start has a syntax of 11 (comment-start).
 	;; Other comments have high-bit flags, so don't == 11.

matlab.el

@@ -1625,21 +1625,21 @@ Travells a cross continuations"
 	(forward-line -1)
 	(matlab-line-end-comment-column (matlab-compute-line-context 1))))))
 
-(defun matlab-line-count-open-blocks (&optional eol)
+(defun matlab-line-count-open-blocks (lvl1 end-lvl1)
   "Return a the number of unterminated block constructs.
 This is any block, such as if or for, that doesn't have an END on this line.
-Optional EOL indicates a virtual end of line."
-  (save-excursion
+Input LVL1 indicates the line we are searching.
+Input END-LVL1 indicates the line whose end we search until."
+  (matlab-with-context-line lvl1
     (let* ((v 0)
-	   (lvl (matlab-compute-line-context 1))
-	   (bound (or eol (save-excursion (matlab-line-end-of-code lvl))))
+	   (bound (matlab-line-end-of-code end-lvl1))
 	   (keyword nil))
       
-      (if (or (matlab-line-comment-p lvl)
-	      (matlab-line-empty-p lvl))
+      (if (or (matlab-line-comment-p lvl1)
+	      (matlab-line-empty-p lvl1))
 	  ;; If this line is comments or empty, no code to scan
 	  0
-	(back-to-indentation)
+	(goto-char (matlab-line-point lvl1))
 	(while (setq keyword
 		     (matlab-re-search-keyword-forward (matlab-keyword-regex 'indent) bound t))
 	  (if (or (and (eq (car keyword) 'mcos)
@@ -1657,14 +1657,15 @@ Optional EOL indicates a virtual end of line."
 		(setq v (1- v))))))
 	v))))
 
-(defun matlab-line-count-closed-blocks (&optional start)
+(defun matlab-line-count-closed-blocks (lvl1 bound-lvl1)
   "Return the number of closing block constructs on this line.
-Argument START is where to start searching from."
-  (save-excursion
-    (when start (goto-char start))
+Argument LVL1 is the line we'll start on (at the end).
+Argument BOUND-LVL1 is where to stop search backwards from."
+  (matlab-with-context-line lvl1
     (let ((v 0)
-	  (lvl1 (matlab-compute-line-context 1))
-	  (bound (save-excursion (matlab-scan-beginning-of-command))))
+	  ;;(lvl1 (matlab-compute-line-context 1))
+	  (bound (matlab-line-point bound-lvl1))
+	  )
       
       (if (matlab-line-comment-p lvl1)
 	  ;; If this is even vagely a comment line, then there is no
@@ -1672,20 +1673,20 @@ Argument START is where to start searching from."
 	  0
 	;; Else, lets scan.
 	;; lets only scan from the beginning of the comment
-	(goto-char start)
 	(matlab-line-end-of-code lvl1)
 
 	;; Count every END from our starting point till the beginning of the
 	;; command.  That count indicates unindent from the beginning of the
 	;; command which anchors the starting indent.
+	(goto-char (matlab-line-end-of-code lvl1))
 	(while (matlab-re-search-keyword-backward (matlab-keyword-regex 'end) bound t)
 	  (let ((startmove (match-end 0))
 		(nomove (point)))
 	    ;; Lets count these end constructs.
 	    (setq v (1+ v))
-	    (if (matlab--scan-block-backward bound) ;;(matlab-backward-sexp t t)
+	    (if (matlab--scan-block-backward bound)
 		(goto-char nomove)
-	      (setq v (1- v)))
+	      (setq v (1- v))) ;; If whole block, uncount the end
 	    ))
 	(if (<= v 0) 0 v)))))
 
@@ -2137,21 +2138,21 @@ See `matlab-calculate-indentation' for how the output of this fcn is used."
     (save-excursion
       (matlab-scan-beginning-of-command lvl1)
       
-      (back-to-indentation)
-      (setq lvl1 (matlab-compute-line-context 1))
-      (let ((cc (matlab-line-count-closed-blocks startpnt))
-	    (bc (matlab-line-count-open-blocks startpnt))
-	    (end (matlab-line-end-p lvl1))
-	    (mc (and (matlab-line-block-middle-p lvl1) 1))
-	    (ec (and (matlab-line-block-case-p lvl1) 1))
-	    (ci (current-indentation)))
+      ;;(back-to-indentation)
+      (let* ((boc-lvl1 (matlab-compute-line-context 1))
+	     (cc (matlab-line-count-closed-blocks lvl1 boc-lvl1))
+	     (bc (matlab-line-count-open-blocks boc-lvl1 lvl1))
+	     (end (matlab-line-end-p boc-lvl1))
+	     (mc (and (matlab-line-block-middle-p lvl1) 1))
+	     (ec (and (matlab-line-block-case-p lvl1) 1))
+	     (ci (current-indentation)))
 
 	;; When CC is positive, and END is false, or CC > 1, then the NEXT
 	;; line should have an indent that matches the context at the beginning
 	;; of the block of the last end.
 	(if (or (> cc 1) (and (= cc 1) end))
-	    (let* ((CTXT (matlab-with-context-line lvl1
-			   (matlab-line-end-of-code lvl1)
+	    (let* ((CTXT (matlab-with-context-line boc-lvl1
+			   (matlab-line-end-of-code boc-lvl1)
 			   (matlab-re-search-keyword-backward
 			    (matlab-keyword-regex 'end) (point-at-bol) t)
 			   (matlab-scan-block-start-context))))