diff --git a/pyttb/export_data.py b/pyttb/export_data.py
index 520e89a2..09dd3d36 100644
--- a/pyttb/export_data.py
+++ b/pyttb/export_data.py
@@ -109,12 +109,7 @@ def export_sparse_array(
     """Export sparse array data in coordinate format."""
     if not fmt_data:
         fmt_data = "%.16e"
-    # TODO: looping through all values may take a long time, can this be more efficient?
-    for i in range(A.nnz):
-        # 0-based indexing in package, 1-based indexing in file
-        subs = A.subs[i, :] + index_base
-        subs.tofile(fp, sep=" ", format="%d")
-        print(end=" ", file=fp)
-        val = A.vals[i][0]
-        val.tofile(fp, sep=" ", format=fmt_data)
-        print(file=fp)
+    # 0-based indexing in package, 1-based indexing in file
+    subs = A.subs + index_base
+    vals = A.vals[:, 0].reshape(-1, 1)
+    np.savetxt(fp, np.hstack((subs, vals)), fmt="%d " * subs.shape[1] + fmt_data)
diff --git a/pyttb/import_data.py b/pyttb/import_data.py
index 7c73c26d..c31cc167 100644
--- a/pyttb/import_data.py
+++ b/pyttb/import_data.py
@@ -99,12 +99,13 @@ def import_sparse_array(
     fp: TextIO, n: int, nz: int, index_base: int = 1
 ) -> tuple[np.ndarray, np.ndarray]:
     """Extract sparse data subs and vals from coordinate format data."""
-    subs = np.zeros((nz, n), dtype="int64")
-    vals = np.zeros((nz, 1))
-    for k in range(nz):
-        line = fp.readline().strip().split(" ")
-        subs[k, :] = [np.int64(i) - index_base for i in line[:-1]]
-        vals[k, 0] = line[-1]
+    data = np.loadtxt(fp)
+    subs = data[:, :-1].astype("int64") - index_base
+    vals = data[:, -1].reshape(-1, 1)
+    if subs.shape[0] != nz:
+        raise ValueError("Imported nonzeros are not of expected size")
+    if subs.shape[1] != n:
+        raise ValueError("Imported tensor is not of expected shape")
     return subs, vals